Operation Primary Physical Science
Department of Physics and Astronomy- Louisiana State University
August, 2000
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Operation Primary Physical Science
Workshop Outline
1. ELICIT:
How Do We Describe Matter?
2. EXPLORE: How Do We Classify Matter?
3. INQUIRE: Is There a Model to Explain Differences Between Solids, Liquids, and
Gases?
A. Searching For Evidence Of Tiny Particles
B. Making Inferences About Particles in Solids, Liquids, & Gases
C. Make Sense
D. Apply
4. INQUIRE: What Can We Learn about Properties of Solids, Liquids, and Gases?
A. Investigating the Properties of Solids
B. Investigating the Properties of Liquids
C. Investigating the Properties of Gases
D. Make Sense
E. Apply
5. INQUIRE: Are Some Properties More Important or More Useful to Know than
Others?
A. Common Properties of Solid, Liquids, And Gases
B. Exploring Mass and Volume
C. Predicting the Behavior of Matter
D. Make Sense
E. Apply
6. REFLECT: Can We Use What We’ve Learned?
August, 2000
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Operation Primary Physical Science
Workshop Sequence
I. ELICIT
How Do We Describe Matter?
The elicitation activity determines, in a non-threatening fashion, participants’
abilities to recognize and to qualitatively and quantitatively describe
properties of matter. Each group is given a different sample of matter to
observe and describe. A variety of measuring tools and other materials are
available at a central location for groups to use if they desire. Groups post
their lists for comparison and discussion.
II. EXPLORE
How Do We Classify Matter?
Groups are given identical sets of matter samples, first to observe and then
to classify or serial order in some meaningful way. Groups visit each others’
workstations to try to figure out the organizational schemes used. All groups
are then assigned to classify the samples as solids, liquids, and gases.
Afterwards, they are asked to list the criteria they used to classify the
samples in this manner. This creates cognitive dissonance as teachers
recognize that some samples (such as flour) do not fit the traditional
characteristics of solids, liquids, and gases that they memorized in school.
This sets the stage for the inquiries that follow. The activity ends by having
the teachers create two lists: 1) a list of their current “Ideas about Solids,
Liquids, and Gases;” 2) a list of relevant “Questions about Solids, Liquids,
and Gases” that they would like to explore further during the workshop.
August, 2000
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Operation Primary Physical Science
Workshop Sequence
III. INQUIRE
Is There a Model to Explain Differences Between Solids, Liquids, and
Gases?
The inquiry begins with the assumption that all teachers have learned, in
their formal education, that matter is composeasd of tiny particles called
atoms and molecules, heretofore referred to simply as “particles”, but
many have never really made a connection between the interactions of
these particles and the properties of the matter they comprise.
A. Searching for Evidence of Tiny Particles
Teachers are polled to find out how many have previously learned that all
matter is made of tiny particles (typically, 100% have) and are probed to
supply evidence to support this idea (typically, very few can). Teachers
then witness a variety of phenomena and discuss how each provides
evidence that matter is indeed composed of tiny particles. Specifically,
teachers observe:
a) an inflated balloon containing a couple of drops of almond extract
which can be smelled from outside the balloon;
b) the mixing of equal volumes of alcohol and water (which results in a
volume slightly less than the sum of the initial volumes);
c) the dissolving of sugar in water;
d) a colored newspaper or magazine picture through a strong magnifier
(which reveals tiny dots of ink).
The activity culminates with a whole group discussion regarding evidence
that matter is made of tiny particles. The actual “particle model of matter”
is not introduced until after the next activity.
August, 2000
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Operation Primary Physical Science
Workshop Sequence
III. INQUIRE
cont.
B. Making Inferences about Particles in Solids, Liquids, and Gases
In this activity, teachers examine the behavior of matter in its different
states in order to make inferences about the differences among the
particles in solids, liquids, and gases. Pairs of teachers rotate through a
series of stations in order to try to explain a variety of phenomena in
terms of what is happening to the particles of matter. As they embark on
this activity, teachers will have already discussed the idea that all matter
is made of tiny particles (atoms and molecules), but they probably have
not yet formally discussed how the arrangement, spacing, and interactions of particles are different in solids, in liquids, and in gases. The
stations in this activity include opportunities for teachers to explore five
important properties: density, strength, change of state, diffusion, and
compressibility. Stations include:
1) noticing the changing water level in a glass tube when the flask into
which it is inserted is placed in hot water, then cold water;
2) adding weights to a hanging thin copper wire;
3) attempting to compress sealed syringes of sand, water, and air;
4) observing a solid room deodorizer;
5) investigating two blocks having identical dimensions but different
masses;
6) adding drops of food coloring to water.
Stations have been carefully chosen to provide a broad base of
experiences involving solids, liquids, and gases. Following the rotation,
teachers share and discuss their ideas in small groups. Each group is
assigned a specific station for which to produce a poster to display what
they think is happening to the particles of the matter. A follow-up
discussion develops a particle model to account for the differences
among solids, liquids, and gases.
August, 2000
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Operation Primary Physical Science
Workshop Sequence
III. INQUIRE
cont.
C. Make sense
Teachers reflect on and make sense of what they have learned during the
inquiry as they revise the posters they made in the previous activity. They
also add to and/or modify their list of “Ideas about Solids, Liquids, and
Gases” and revisit their list of “Questions about Solids, Liquids and Gases.”
D. Apply
Teachers work in groups to complete a paper and pencil activity in which
they must make a connection between the particle model and the properties
of solids, liquids, and gases: flask of air and same flask from which some
air has been evacuated, student’s drawing of the particles in water, a large
solid and a small solid having identical masses.
IV. INQUIRE
What Can We Learn about Properties of Solids, Liquids, and Gases?
Teachers will investigate the properties of solids, then liquids, then gases.
As they discover properties, they will try to make sense of them in terms of
the particle model. Teachers will apply what they have learned by analyzing
and evaluating different brands or kinds of a grocery store product in terms
of desirable properties.
A. Investigating the Properties of Solids
Given an assortment of solids, as well as other materials and tools,
teachers generate and discuss testable questions they might try to
answer about the properties of solids. Each group of teachers selects
one question to investigate about solids, designs and conducts an
investigation to answer the question, and then presents what they did
and what they found out. These initial investigations of solids may lead
to further investigations. Discussions, which accompany the
investigations, help teachers to develop clear definitions of properties consistent with those of the scientific community - for properties such as
hardness, elasticity, tensile strength, malleability, absorbency, etc., and
simple procedures for quantitatively comparing solids in terms of these
properties. At the end of the activity, teachers consider how the particle
model can be used to explain some of the similarities and differences in
the properties of solids that they observed. (Teachers should be informed
that this simple model is not sufficient to explain all of their observations;
many properties are determined by additional factors such as the size of
the particles, the way electrons are distributed in particles that are atoms,
the way atoms are arranged in particles that are molecules, etc.)
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Operation Primary Physical Science
Workshop Sequence
IV. INQUIRE
cont.
B. Investigating the Properties of Liquids
Teachers use the materials and tools provided to freely explore the
properties of three different clear liquids: water, isopropyl alcohol, and
glycerin or mineral oil. When teachers have finished exploring, they discuss
similarities and differences in the properties of liquids. This includes a
discussion of cohesion, adhesion, surface tension, viscosity, and rate of
evaporation. At the end of the activity, teachers consider how the particle
model can be used to explain some of the similarities and differences in the
properties of liquids that they observed.
C. Investigating the Properties of Gases
A series of activities and demonstrations show that gases are fluids, exert
pressure, have a very small mass for the amount of volume they occupy,
take the shape of their container, diffuse rapidly, and move from areas of
higher pressure to lower pressure. After viewing and discussing the
demonstrations, teachers consider how the particle model can be used to
explain some of the similarities and differences in the properties of gases
that they observed. Teachers then compare the properties and behaviors of
air, carbon dioxide, and helium.
D. Making Sense
Teachers are given the opportunity to reflect on and make sense of what
they have learned during the inquiry. They also add to and/or modify their
list of “Ideas about Solids, Liquids, and Gases”, and revisit their list of
“Questions about Solids, Liquids, and Gases.”
E. Applying
In this paper and pencil exercise, teachers list the properties that are
desirable in a clear, plastic food wrap. They then design a test that can be
used to compare different brands of food wrap in terms of one selected
property.
V. INQUIRE
Are Some Properties More Important or More Useful to Know than Others?
After having extensively examined properties of solids, liquids, and gases,
participants consider whether some properties are more important, or
useful, than others.
August, 2000
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Operation Primary Physical Science
Workshop Sequence
V. INQUIRE
(cont.)
A. Common Properties of Solids, Liquids, and Gases
Teachers work in groups to prepare a Venn diagram that shows the
properties of solids, liquids, and gases. Diagrams are compared and
critiqued and the idea is developed that all matter - solids, liquids, and
gases - have in common the properties of mass and volume. The definition
of matter as “anything that has mass and takes up space” is discussed in
this light. Everyday situations in which mass or volume is used to describe
the amount of matter (such as at the grocery store), and ways of measuring
mass and volume, are also discussed.
B. Exploring Mass and Volume
Teachers investigate whether there is a relationship between mass and
volume. Each group of teachers is assigned a different kind of matter (a
solid that is insoluble in water, or a liquid) to investigate, such as aluminum
foil, water, oil, Styrofoam ®, or paper clips. No specific instructions are given,
but each group is supplied with a balance, a metric ruler, one or more
graduated cylinders, and (optionally) an overflow can. After about 20
minutes, groups take turns sharing their procedures and findings. The
concept of density is developed and the densities of the various materials
used in the activity are compared. The idea that density - unlike mass or
volume - is an intensive property is discussed. The teachers then use
density to identify an unknown metal. Real world examples are presented of
how density is used to determine the identity or purity of materials.
C. Predicting the Behavior of Matter
This activity provides an example of how certain properties can be useful in
predicting the behavior of matter. The activity develops the idea that density
can be used to predict floating and sinking behavior. Each group of teachers
is supplied with water to which blue food coloring has been added and
mineral oil, and is asked to predict how the two liquids will layer if placed
together. Before trying this, groups share their predictions and the reasons
for them. After testing their predictions, groups compare the densities of the
liquids to the order in which the liquids can be layered. The difference
between viscosity and density is discussed. Next, participants test whether
the idea just developed -- the fact that liquids will layer based upon
differences in density -- can be extrapolated to include a mixture of solids
and liquids. Participants are given a piece of opaque white plastic from a
bleach bottle. Participants observe what happens when the plastic piece is
put into a clear bottle containing the blue water and mineral oil. (The white
plastic can be cut into the shape of a boat before inserting to make a wave
bottle for a nice “Make and Take” activity.) Afterwards, participants observe
a silent demonstration conducted by the workshop leader.
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Operation Primary Physical Science
Workshop Sequence
V. INQUIRE
cont.
C. (continued)
A candle is cut into two unequal pieces (one large and one small) and the
pieces are placed into two different beakers, each containing an unidentified
clear liquid (one beaker contains water and the other alcohol). The
participants are asked to account for their observations and to make a
prediction as to what will happen if the two candle pieces are switched.
After the demonstration is complete, participants discuss their explanations
and predictions. The activity ends by having the participants consider
whether the floating and sinking phenomena they have observed can be
explained in terms of the particle model of matter developed earlier in the
workshop.
D. Making Sense
Teachers are given the opportunity to reflect on and make sense of what
they have learned during the inquiry. They begin this process by observing
and trying to explain a cylinder containing a golf ball layered between two
liquids (water and salt water). They also add to and/or modify their list of
”Ideas about Solids, Liquids, and Gases” and revisit their list of “Questions
about Solids, Liquids, and Gases.”
E. Applying
Teachers are given samples of the 6 types of recyclable plastics and are
asked to invent a scheme, using varying concentrations of salt water, to
identify an unlabeled sample of one of these. They are then given an
unknown sample to try to identify using the scheme they have designed.
August, 2000
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Operation Primary Physical Science
Workshop Sequence
VI. REFLECT
Can We Use What We’ve Learned?
Teachers, working in their groups, reflect on what they have learned during
the workshop by finalizing their list of “Ideas about Solids, Liquids, and
Gases” and, for each idea listed, citing one or more examples of evidence
to support the idea. Thus, teachers are indicating not only WHAT they
know, but also HOW they know. When finished, the workshop leader
distributes the list of “Key Ideas”. Teachers compare the ideas they
developed with the “Key Ideas” (which is a list of the science ideas that the
workshop leader(s) hoped they would develop). The workshop leader tries
to address any questions that arise from this comparison. It is expected that
there will be differences in the phrasing and terminology used on the two
lists, and the workshop leader should address these differences. The
workshop culminates by having the teachers take a final look at their list of
“Questions about Solids, Liquids, and Gases”. Some of these questions
may be addressed later in the second and third workshops on matter. The
workshop leader may choose to address other questions at this time or,
depending on the question(s), have the participants talk about how they
might go about trying to answer the question(s) themselves through further
investigations.
NOTE: The entire content portion of the workshop as outlined requires
about 20 hours of workshop time. Following are suggestions for
reducing the length of the workshop:
1.
Eliminate INQUIRE V-E. This application activity does not
introduce any new science ideas, but rather is intended to let teachers
practice using their new ideas in a novel and authentic context. This
reduces the length of the workshop by 1 hour.
2.
Eliminate ELICIT I. While this activity sets the stage for the
remainder of the workshop, it can be omitted. If this is done, EXPLORE II
becomes the first activity of the workshop and it can suitably serve the dual
purpose of both elicitation and exploration. This reduces the length of the
workshop by
about .5 hours.
3.
Shorten INQUIRE IV-C by eliminating some of the demonstrations
or activities underneath each section, but only if teachers have a good
understanding of the ideas developed. This could reduce the length of the
workshop by about .5 hours.
August, 2000
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Operation Primary Physical Science
Master Materials List
I. Elicit
II. Explore (Cont.)
Solid substances having very different properties (one solid per
group)
EXAMPLES
- paper clip
- moth ball
- sugar cube
- eraser
- sheet of colored construction paper
- piece of Plexiglas ®
- aluminum foil sheet
- plastic Easter egg
- rock salt
- Styrofoam® peanut
- cotton ball
At a common table:
• hand lenses
• balances
• metric rulers and/or measuring tapes
• graduated cylinders
• conductivity tester
• magnet
• small beakers or other containers
• water
• scissors
• microscope (or binocular scope)
Optional:
• alcohol
• tin snips
• sandpaper
• metal file
II. Explore
For each group, six or seven of the following items, each
contained in a Ziploc ® bag:
• metal bolt or washer
• rocks
• sugar or Kool-aid
• plasticene or modeling clay
• flour
• balloon or rubber bands
• colored shampoo
• vinegar
• glue
• rubbing alcohol
• cornstarch and water mixture
• shaving cream
• air
• helium
August, 2000
NOTE: Use whatever is interesting and what you have access
to. Make up identical sets of items for the groups. Ensure that
sets have a good range of materials and include solids, liquids,
and gases. Be sure to include items that are difficult to classify
as solid, liquid, or gas (such as the flour, plasticene, and
shaving cream).
III. Inquire
III-A. Searching for Evidence of Ttiny Particles
For each group of 3-4 teachers
• large round balloon
• almond or vanilla extract
• beaker or clear container of water
• sugar (individual restaurant packs are recommended)
• stirring rod
For workshop leader demonstration:
• clear glass or plastic tube with end caps (1-3 cm
diameter, at least 50 cm long)
• isopropyl alcohol
• graduated cylinder for measuring above liquids
• meter stick or metric tape
III-B. Making Inferences about Particles in
Solids, Liquids & Gases
Station 1 - Water
• hot plate on LOW setting
• pan of water
• bowl of ice
• tongs
• flask capped w/rubber stopper into which glass tube
has been inserted
• colored water
• glass marker
NOTE: Flask should contain enough colored water to
partially fill the glass tube.
Station 2 - Wire
• 0.5 m lengths of copper wire, about 32 gauge
• meter stick
• ring stand
• clamp to attach ring stand to table
• weight hanger
• slotted masses (100g - 500g)
NOTE: 32 gauge copper wire should require a force of
about 20 N to break
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Operation Primary Physical Science
Master Materials List
III. Inquire (Cont.)
IV. Inquire
Station 3 - Syringes
• 3 plastic syringes (100 cm3 capacity or greater)
• epoxy
• sand
• water
NOTE: The three syringes should be half -filled with sand,
water, and air and the ends should be sealed with epoxy. For
the air syringe, depress the plunger half -way and seal. The
plungers in the sand and water syringes should be pressed
down to the material with no air left and sealed.
IV-A. Investigating the Properties of Solids
Assign one of the following sets to each group:
• 4 different minerals — samples such as quartz,
feldspar, talc, calcite, gypsum, etc.
• 4 different woods — blocks or strips of ash, pine,
balsa, cedar, etc.
• 4 different white papers - poster paper, blotter paper,
paper towel, copy paper. etc.
• 4 different metals - strips of copper, aluminum, lead,
zinc, etc.
• 4 different cloths — squares of cotton, rayon, polyester ,
knit, nylon, chamois, rubber sheeting, etc. (include
samples that will stretch)
• 4 different threads/wires of almost identical
diameters — cotton, nylon, fishing line, thin copper
wire, etc.
Station 4 - Air Freshener
• solid air freshener with adjustable container
NOTE: Remind participants to close after use.
Station 5 - Blocks
• blocks that have the same dimensions but made of
different materials like:
iron, wood, Styrofoam® ,
and brick
• balance
• metric ruler
Station 6 - Colored Water
• food coloring
• dropper
• large container of water (1000 ml beaker)
• several empty small beakers or clear plastic cups
• Optional: chilled food coloring
For workshop leader:
• transparency of “A Particle Model of Matter”
• overhead projector
For each group:
• poster or chart paper
• markers
III-C. Make Sense - None
III-D. Apply - None
At a central table: balances, tennis ball, pennies, metric
rulers, scissors,vinegar,support stands, masking tape,dilute
hydrochloric acid,hooked weights, porcelain streak plates*,
isopropyl alcohol,beakers,embroidery hoop,thumbtack,couple
of nails, wax paper
IV-B. Investigating the Properties of Liquids
For each group:
•
water*
•
•
•
•
•
•
•
•
•
•
•
glycerin* (or a clear, colorless oil)
isopropyl (rubbing) alcohol*
small containers for the liquids (such as clear
plastic cups)
kosher salt
sugar
3 dropper pipettes (one for each liquid)
food coloring (any color)
waxed paper
wooden or plastic stirrers (coffee stirrers will work)
paper towels
notebook or copy paper
* It is convenient if liquids can be provided in dropper
bottles.
NOTE: You may want to place all materials at a central
station — with the possible exception of the three liquids —
for participants to pick up as needed.
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Operation Primary Physical Science
Master Materials List
IV. Inquire (Cont.)
V. Inquire (Cont.)
IV-C. Investigating the Properties of Gases
Part One - Blow Up a Teacher! (demo)
For whole group:
• 10 strong gallon-size Ziploc ® bags
V-B. Exploring Mass and Volume
For each group:
• balance
• graduated cylinder(s)
• metric ruler
• overflow can (optional)
• unknown metal sample
• a different kind of matter to investigate**
Examples: water
different sizes of Styrofoam® blocks
paper clips
oil
blocks of wood
copper shot
**Groups will need a sufficient amount to have five differentsized samples of the matter. Keep the purpose of the activity
in mind when selecting matter samples. Choose materials
that for various reasons are difficult to measure (such as a
material that floats in water) so that the participants will have
to search for ways to overcome such difficulties in addition to
seeking an answer to the investigation question.
•
•
•
•
1 heavyweight 30 gallon trash bag
10 drinking straws
flexible adhesive tape
2 lightweight tables (stable and strong)
Part Two - A New Way to Inflate a Balloon (demo)
For whole group:
•
small piece of dry ice
•
•
•
tongs and mitts for handling dry ice
•
•
•
•
strawberry gelatin powder (Jell-O® )
large oblong balloon
1000 ml graduated cylinder (optional)
Part Three - Strawberry Gas (demo)
•
petri dish
water
stirrer
overhead projector and screen
Part Four - Bottle Blowing (demo)
• clear soda bottle (16 oz or half -liter)
• small wad of paper
Part Five - Comparing Gases
•
air pump
•
helium tank
•
carbon dioxide cartridge or other source
•
bottles of air, helium and carbon dioxide*
•
birthday candles
•
matches or lighter
•
bubble solution with bubble blower
•
balloons (optional)
•
aquarium tank
•
dry ice
IV-D. Making Sense
•
None
IV-E. Applying
•
None
V. Inquire
V-A. Common Properties of Solids,
Liquids, and Gases
For each group:
• sheet of chart or poster paper
• marker
August, 2000
V-C. Predicting the Behavior of Matter
For each group:
•
beaker or cup of mineral oil
•
beaker or cup of blue water (water to
which food coloring is added)
•
empty beaker
•
piece of white plastic cut from bleach
bottle
•
clear and clean soda bottle, 16 oz.
•
scissors
For whole group
• large (600 ml - 1000 ml) beaker of water
• large (600 ml - 1000 ml) beaker of alcohol
• utility candle
• knife (for cutting candle into a small and large piece)
• tongs
V-D. Mak E Sense
For whole group:
• tall cylinder containing salt water, golfball, and distilled water
(a clear plastic tennis ball can works well for the container)
V-E. Apply
For each group:
• samples of each plastic, #1-#6 (see activity sheet for
sources)
• beakers or other containers
• water
• tongs
• unknown plastic sample
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Operation Primary Physical Science
Key Ideas About Nature of Matter
1. Matter exists in three common states — solid, liquid, and gas. Each state is described
by a set of distinguishing properties.
•
Each state of matter has distinguishing characteristics, although different samples of matter
having the same physical state may vary widely in other properties.
•
Solids have a definite shape, occupy a definite volume, are non-compressible, and have
multiple free surfaces.
•
Liquids flow readily and take the shape of their container, occupy a definite volume, are
non-compressible, have a single free surface, and find their own level.
•
Gases have no definite shape or volume, have no free surfaces, diffuse rapidly to fill a space
uniformly, can be compressed, have a small mass for their volume, exe rt pressure on
surfaces with which they come in contact, and have a small mass for their volume. Gases
move from areas of higher concentration to areas of lower concentration (or higher pressure
to lower pressure).
•
Some materials are not easily classified as a solid, liquid, or gas. Many of these are actually
a mixture of two or more substances that have different physical states. Jello, for example,
is made by mixing a powdery solid with liquid water.
2. The states of matter and their distinguishing properties can be explained by a particle
model of matter.
All matter is composed of tiny particles (atoms or molecules) that are in constant motion.
These particles are much too small to be seen with an ordinary microscope. A single drop of
water, for example, is made of approximately 3,000,000,000,000,000,000,000 (3 X 1021) water
particles.
In a solid, strong forces of attraction hold the particles in a tightly packed and regular
arrangement. Movement of particles is restricted to vibration about a fixed position. This
explains the definite shape and definite volume of solids. It also accounts for why solids are
dense (a lot of matter packed into a space) and noncompressible (the particles are already very
close together). To form a mental model for the particles of a solid, think about apples packed
in layers in a box that is in a truck driving on a gravel road.
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Operation Primary Physical Science
Key Ideas About Nature of Matter
2. (Cont.)
In a liquid, the particles are not so strongly held together and can slide freely past one another,
but cannot easily move apart from one another. This explains how liquids are able to flow and
take the shape of their container while maintaining a definite or constant volume. A mental
model for the particles of a liquid may be to think about the plastic balls in a “ball pool” in
which young children are playing.
In a gas the particles are independent of one another. There is very little or no attraction
between gas particles. Particles move in random directions at very high speeds. Particles of a
gas at room temperature may move at about 500 meters per second (or about 1000 miles/hour).
The particles move as far apart from one another as the container space allows, moving from
an area of higher concentration to an area of lower concentration until they are uniformly
distributed in the space available. They collide frequently with one another and with the inside
surfaces of their container. The arrangement and motion of particles of a gas explains why
gases are able to rapidly diffuse and how gases exert pressure. It also accounts for why gases
have a very low density, or small mass for their volume. The particles are so spread out that
most of the gas is empty space. This empty space between particles is what allows a gas to be
compressed into a smaller space. To form a mental model for particles in a ga s, imagine lottery
balls whizzing around inside the dispenser.
The particle model described above is sometimes referred to as the kinetic theory.
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Key Ideas About Nature of Matter
3. While substances having the same physical state share the distinguishing properties of
that state, they may vary widely in other properties. Some of these variations in properties
can also be explained by the particle model.
Solids vary in properties such as hardness, tensile strength, density, elasticity, conductivity,
solubility, porosity, etc. Liquids vary in properties such as cohesion, adhesion, viscosity,
density, solubility/miscibility, rate of evaporation, etc. Gases vary in rate of diffusion, density,
etc.
The particle model can help explain some of these variations in properties. For example,
difference in the tensile strength of solids is related to a difference in the strength of attraction
between the particles constituting the solids. Difference in the viscosity of liquids, which
results from friction between particles as they slide past one another, is related to a difference in
the length of the particles. Difference in the rates of diffusion of gases can be explained by
differences in the mass of the particles constituting the gas. More massive particles have less
speed, so a gas that has more massive particles does not diffuse as rapidly.
4. Every substance has a unique set of properties that can be used to identify the
substance, to determine ways in which it may be used, and to predict its behavior in
certain situations.
Substances differ from one another in characteristic properties such as color, density, freezing
point, and solubility. Characteristic properties do not depend on the quantity of material present.
(Mass and volume are, consequently, not characteristic properties.)
Density is a particularly useful characteristic property. The density of a substance describes the
amount of matter in a certain volume of the substance. Density = mass/volume. The density of
a substance depends on both the mass of the particles of which it is made and the way in which
these particles are arranged or packed together. The density of a substance can be used to
predict sinking and floating behavior. A substance will float in a fluid of greater density, and
sink in one of lesser density. The density of water is 1 g/ml (at 4 oC). An object with a density
greater than 1 g/ml will sink in water, while a substance with a density of less than 1 g/ml will
float in water. If an object is made of more than one substance, the density of the object can be
calculated by dividing the total mass of the object by the total volume the object occupies. The
density of a substance may change with even slight changes in temperature. This is because
when a substance is heated, the particles of which it is composed move faster and further part.
August, 2000
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Operation Primary Physical Science
Key Ideas About Nature of Matter
4. (Cont).
Characteristic properties are useful in identifying a substance. Aluminum, for example, is a
malleable, silver metal that has a density of 2.7 g/ml and melts at a temperature of 660oC. It
doesn’t matter if you have a pea-sized pellet of aluminum or a gigantic block of aluminum; its
characteristic properties are constant. Thus, if you have a piece of unidentified silver-colored
metal - no matter how large or small — you can determine if it is aluminum by testing its
melting point and/or its density. You can use these same tests to determine the purity of a
substance. The collective characteristic properties of a substance also determine appropriate
uses for the substance. Aluminum is used for the body of aircraft because it is malleable,
strong, and lightweight.
August, 2000
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Operation Primary Physical Science
I. ELICIT How Do We Describe Matter?
GOAL:
MATERIALS:
To elicit what participating teachers know, what
they think they know, and what they do not know
about properties and measurement of matter.
OVERVIEW:
Teachers are divided into collaborative groups and
will work within these groups for the duration of
the workshop. For this elicitation activity, each
group is given a different solid to observe and
describe. Measuring instruments and other
materials are available at a central location for
groups to optionally use. After about 15 minutes,
groups post their lists of characteristics for
discussion and comparison.
SCIENCE IDEAS
•
•
•
There is a broad and rich array of
properties of matter.
Many properties can be measured.
Some properties vary with the amount of
matter present, while other properties are
independent of the quantity of matter.
Solid substances having very
properties (one solid per group)
different
EXAMPLES
- paper clip
- moth ball
- sugar cube
- eraser
- sheet of colored construction paper
- piece of Plexiglas ®
- aluminum foil sheet
- plastic Easter egg
- rock salt
- Styrofoam ® peanut
- cotton ball
At a common table:
• hand lenses
• balances
• metric rulers and/or measuring tapes
• graduated cylinders
• conductivity tester
• magnet
• small beakers or other containers
• water
• scissors
• microscope (or binocular scope)
Optional:
• alcohol
• tin snips
• sandpaper
• metal file
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Operation Primary Physical Science
I. ELICIT How Do We Describe Matter?
Divide participants into collaborative
groups of 2-4 and give each group a
different solid sample.
Tell participants that th ey will have
about 15 minutes to examine their
sample of matter. You can later give
them additional time if needed. Instruct
groups on how they should display their
list for sharing. It is suggested they be
supplied with chart paper, markers, and
tape for writing and posting their list;
another option would be to have groups
write their lists side-by-side on a chalk
or dry erase board.
I. How Do We Describe Matter?
1. Examine the sample of matter your
group has been given. Try to describe
your matter as completely as possible.
Your workshop leader will point out some
measuring tools and other items that you
may want to use. Make a list of one- or
two-word characteristics that best
describe your matter. Be prepared to
post your list so it can be shared with
other groups.
Once groups have posted their lists, you
might want to point out that the
“characteristics” they have listed would
be referred to by scientists as
“properties.”
2. Once all of the lists are posted,
examine them for similarities and
differences. Try to answer the following
questions:
- Do these lists give you ideas for
additional characteristics that
you could have put on your list?
- Which of the characteristics on
your list describe the object
your group observed, and which
describe the material of which
object is made?
- Did you list any characteristics
that would change if you had a
different amount of matter in
your sample?
- Are any of your observations
quantitative (involve making a
measurement)? What is the
advantage of making
quantitative observations?
- Are there any characteristics
that appear on ALL of the lists?
After groups have had some time to
consider each of the questions, lead a
large group discussion in which groups
can share their ideas. While “teaching
opportunities” will certainly arise during
the discussion, remember that the
purpose of this first activity is to elicit
the participants’ ideas and to serve as an
“ice breaker” that will increase the
participants’ comfort level with the
workshop. There will be plenty of
“teaching moments” later on in the
workshop.
August, 2000
© OPPS - Louisiana State University
- Did different groups use
different words to describe the
same characteristics? If so,
what term do scientists use to
describe this characteristics?
Be able to share your thoughts in a whole
group discussion.
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
SCIENCE IDEAS
GOAL:
To allow teachers to freely explore samples of
matter in each of the physical states, to get them to
question their understanding of solids, liquids, and
gases, and to provide experiences which lead to
questions that can be investigated in other
workshop activities.
•
•
OVERVIEW:
Groups are given identical sets of matter samples
to first observe, and then to classify or serial order
in some meaningful way. Groups visit each
other’s workstations to try to figure out the
organizational schemes used. All groups are then
assigned to classify the samples as solids, liquids,
and gases. They are asked to list the criteria they
used to classify the samples in this manner. This
creates cognitive dissonance as teachers recognize
that some samples (such as flour) do not fit the
traditional characteristics of solids, liquids, and
gases that they memorized in school, and this sets
the stage for the inquiries that follow. The activity
ends by having the teachers create two lists:
•
•
•
Matter may be classified in a variety of
ways; one way of classifying matter is by
physical state.
Solids share some common properties
but also have a variety of different
properties. Common properties of solids
include definite volume, definite shape,
noncompressibility, multiple free surfaces
and some degree of hardness.
Liquids share some common properties
but also have a variety of different
properties. Common properties of liquids
include definite volume, fluidity, ability to
take the shape of their container, one free
surface, and noncompressibility.
Gases have common properties that
include no definite shape, no definite
volume, fluidity, no free surfaces and
compressibility.
Not all matter can be easily classified as a
solid, liquid, or gas; some matter has
characteristics of more than one physical
state.
1) a list of their current “Ideas about Solids,
Liquids, and Gases”;
2) a list of relevant “Questions about Solids,
Liquids, and Gases” that they would like to
explore further during the workshop.
August, 2000
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
MATERIALS:
For each group, six or seven of the following
items, each contained in a Ziploc ® bag:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
metal bolt or washer
rocks
sugar or Kool-aid
plasticene or modeling clay
flour
balloon or rubber bands
colored shampoo
vinegar
glue
rubbing alcohol
cornstarch and water mixture
shaving cream
air
helium
NOTE: Use whatever is interesting and what
you have access to. Make up identical sets
of items for the groups. Ensure that sets
have a good range of materials and include
solids, liquids, and gases. Be sure to include
items that are difficult to classify as solid,
liquid, or gas (such as the flour, plasticene,
and shaving cream).
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
Provide each group with a set of matter
samples in Ziploc® bags. You may want
to have all of the matter samples at a
common table and call for a person from
each group to come to the table and get
a set.
II. How Do We Classify Matter?
1. On your own, look at the samples of
matter your group has been given. How
are they similar? How are they different?
Brainstorm ways that you might serial
order or group the samples based on their
observable characteristics.
Clarify the difference between “serial
ordering” and “grouping.”
Allow each group a few minutes to
decide how they want to classify or serial
order the samples to display for other
groups to see. Encourage them to be
innovative in their classifications.
3. Visit other groups’ displays and try to
figure out the reasons for them.
Ziploc™ bags with samples
Lead this part of the activity from a
position where everyone can see the list
being built on a flipchart, chalkboard, or
overhead transparency.
August, 2000
2. In your group, share your ideas for
organizing the samples. Pick one method
of organizing to show to the other groups.
Try to think of a way that the other groups
may not have thought of. Display your
actual samples in this way on your table.
Other groups will visit your display and try
to figure out the reason behind your
organizational scheme.
© OPPS - Louisiana State University
4. Make a whole-group list of the different
ways in which groups have grouped or
serial ordered their samples of matter.
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
Activity Follow-up
Classifying Matter
Ask participants to think of ways that they may have learned in chemistry that scientists classify
matter. Examples of ways participants might identify include:
- solids, liquids, gases
- elements, compounds, mixtures
- edible and inedible
- animal, vegetable, mineral
- transparent, translucent, opaque
- flammable, flame resistant
Have participants discuss WHY we might want to organize matter in a particular way. Have
them consider and discuss
- ways in which matter is organized in everyday life, such as in a grocery store,
the local hardware store, their clothes closet, etc.
- why chemists might need to organize chemicals in their storeroom in a particular way
- whether it is always easy to classify items (for example, there are items at the
grocery store that are always hard to locate because they don’t logically fit into a
single category -- such as flaked coconut).
Draw out the idea that classification schemes are ways that people, including scientists, have
found to organize items in a way that makes sense and is useful. Chemists classify matter in a
certain way for a variety of reasons -- to predict the behavior of certain substances based upon
the way they know other substances in the same category behave, to be able to communicate
information about a whole group of chemicals rather than having to give information for every
individual chemical (such as the way ALL liquefied gases should be handled, stored, and
transported), etc.
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
Activity Follow-up (Cont.)
Solids, Liquids, and Gases
Inform participants that they are now going to try to classify their samp les of matter in the same
way and see if they all agree. Specifically, each group should classify their matter samples as
solids, liquids, and gases. (It is alright if some groups previously classified their matter this way.)
Tell them to arrange their samples into three distinct groups. Give them a couple of minutes to do
this.
When they have finished, let them look to see if all groups classified their samples in the same
way. Hope that there will be some differences. If not, ask teachers to discuss whether they found
any of the samples difficult to classify, and how they made a decision as to which category to
place the sample in. This should lead into a discussion of the need for clear criteria when
classifying.
Give groups time to identify the criteria they used to determine what was a solid, a liquid, and a
gas? In other words, when they picked up a partic ular sample of matter, what in their
subconscious mind let them know that it should be put into the solid category, for example.
Anticipate that this will be the first time that many of the teachers have REALLY examined
solids, liquids and gases and thought about them in terms of common properties. Almost all
groups will begin this task by recalling properties they memorized in school — definite volume,
definite shape, etc. Most teachers will find it very disconcerting to recognize that a number of the
matter samples cannot be neatly pigeon-holed into one of the three categories. Spend time letting
the teachers talk about some of the specific things they find problematic. Let them wrestle with
questions such as
— Why can you pour sugar if it is a solid?
— How can you classify a cotton ball as a solid if it can be squeezed into a smaller space?
— How should you classify a foam?
— Will the air in the baggie occupy more space if I open the baggie?
Help them in thinking through and finding answers to their questions. Remind them that
classification systems are human inventions and there are almost always exceptions. Point out
that the way one describes a material often depends on the scale at which one looks at it; thus a
grain of sand would be described differently than a bucket of sand. Participants will have an
opportunity later in the workshop to address questions that they cannot answer at this time.
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
Activity Follow-up (Cont.)
Solids, Liquids, and Gases (cont.)
Each group should now list their criteria for solids, for liquids, and for gases. It is suggested
that you have them write these on chart paper for posting and comparison. From these, ask
teachers to help you develop a consensus list of ideas about the common properties of solids, of
liquids, and of gases. Make sure that all teachers are comfortable with the language included
on the consensus list. Below are some properties that might be included:
SOLIDS
Definite Volume
Definite shape
Noncompressible
Multiple free surfaces
Hardness*
LIQUIDS
Definite Volume
No definite shape
Noncompressible
One free surface
Fluidity
GASES
No definite Volume
No definite shape
Compressible
No free surface
Fluidity
*This is listed because, in our extensive interviews with primary grade children, it was the most common
term used to characterize solids. Some children even gave clear reasons for this characterization; for
example, when asked if paper was hard, a 1st-grade girl explained, “Yes, because it’s harder to poke
your finger through a sheet of paper than to poke it through water or air”. Indeed, all solids have some
degree of hardness.
Once the consensus list has been developed, ask teacher groups to begin two lists on chart paper
that they will continually revisit and revise during the course of the workshop:
List 1:
“Our Ideas about Solids, Liquids, and Gases” - This should include the
key ideas, written in complete sentences, that the group already knew or
learned during the elicitation and exploration activities. Stress the
importance of writing ideas as complete sentences; an incomplete sentence
represents an incomplete idea.
List 2: “Our Questions about Solids, Liquids, and Gases” - This should be a list
of questions that the group would like to investigate further and have
answered during the workshop.
Emphasize the importance of these lists to the overall success of the workshop. Explain that the
lists will help you, as the workshop leader, to determine the pace, depth and direction that the
remainder of the workshop should take.
Culminate the activity by letting groups, in turn, share their lists.
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Operation Primary Physical Science
II. EXPLORE How Do We Classify Matter?
Activity Follow-up (Cont.)
Conclusion
As a workshop leader, you need to consider these lists as you begin the main portion of the
workshop. Are all of the investigations/activities necessary? Do additional activities or
demonstrations need to be added? Do you need to “make a note” to remember to address
particular questions at a specific point in the workshop? Are there indications that
participants will work through the planned inquiries in more/less time than you initially
anticipated?
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Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
GOAL:
To develop teachers’ understanding of and ability
to use a particle model of matter to account for the
differences between solids, liquids, and gases.
OVERVIEW:
The inquiry begins with the assumption that all
teachers have learned in their formal education
that matter is composed of tiny particles called
atoms and molecules, (hereinafter referred to
simply as “particles”), but many have never really
made a connection between the interactions of
these particles and the properties of the matter
they comprise. The inquiry begins with a search
for evidence that matter is indeed composed of
tiny particles. Next, teachers rotate through a
series of stations where they examine the behavior
of matter in its different states in order to make
inferences about the differences between the
particles in solids, liquids, and gases.
III-A. Searching for Evidence of Tiny
Particles
Teachers observe
a) an inflated balloon containing a couple of drops
of almond extract which can be smelled from
outside the balloon;
b) the mixing of equal volumes of alcohol and
water (which results in a volume slightly less than
the sum of the initial volumes);
c) the dissolving of sugar in water;
d) a colored newspaper picture.
They discuss how each of these provide evidence
that matter is not continuous but is made of tiny
discrete particles.
August, 2000
III-B. Making Inferences about Particles in
Solids, Liquids, and Gases
This activity is adapted from one carefully
researched and developed at the CLIS Center at
the University of Liverpool for its “Particulate
Nature of Matter” module. Pairs of teachers rotate
through a series of stations in order to try to
explain a variety of phenomena in terms of what is
happening to particles of matter. As they embark
upon this activity, teachers will have already
discussed the idea that all matter is made of tiny
particles (atom and molecules), but have not yet
formally discussed how the arrangement, spacing,
and interactions of particles are different in solids,
liquids, and gases. The stations in this activity
include opportunities for teachers to explore five
important properties: density, strength, change of
state, diffusion, and compressibility. Stations
include
1) noticing the changing water level in a glass
tube when the flask into which it is inserted is
placed in hot and then cold water;
2) adding weights to a vertically suspended copper
wire;
3) attempting to compress sealed syringes of sand,
water, and air;
4) observing a solid room deodorizer;
5) investigating two blocks having identical
dimensions but different masses;
6) adding drops of food coloring to water.
Stations have been carefully chosen so that a
broad base of experiences will be available to the
teachers in order to construct a model to account
for the differences among solids, liquids, and
gases. Following the rotation, teachers share and
discuss their ideas in small groups. Each group is
assigned to a specific station for which to produce
a poster to display what they think is happening. A
follow-up discussion develops a particle model
that might be used to account for differences between solids, liquids, and gases.
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Operation Primary Physical Science
III. INQUIRE Is There a Model To Explain Differences Between
Solids, Liquids, and Gases?
III-C. Make Sense
Teachers reflect on and make sense of what
they have learned during the inquiry as they
revise their posters from the previous activity.
They also add to and/or modify their list of
“Ideas about Solids, Liquids, and Gases” and
revisit their list of “Questions about Solids,
Liquids and Gases.”
III-D. Apply
Teachers work in groups to complete a paper and
pencil activity in which they must make a
connection between the particle model and the
properties of solids, liquids, and gases.
Specifically, the teachers :
1) draw particles in pictures representing a flask of
air and the same flask from which some air has
been evacuated;
2) analyze a student’s drawing of the particles in
water;
3) make inferences about the particles in a large
solid and a small solid having identical masses.
SCIENCE IDEAS
•
•
•
•
•
•
•
•
August, 2000
All matter is composed of tiny particles
which are in constant motion.
Depending on the state of matter at a
given temperature, there are differing
degrees of attraction between
particles.
Particles in a solid are closely packed,
arranged in regular arrays, vibrate
about a fixed point, and are strongly
attracted to one another.
Particles in a liquid are closely packed,
arranged irregularly, move past one
another, and are only weakly attracted to
one another.
Particles in a gas are well spaced out,
arranged at random, move very rapidly,
and have virtually no attraction for one
another.
The particles that make up a given
substance are the same regardless of
whether the substance is in the solid,
liquid or gas state.
As matter is heated, the energy of the
particles increases and they move faster
and farther apart.
As matter changes from a solid to a liquid
to a gas, the energy of the particles
increases.
© OPPS - Louisiana State University
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Operation Primary Physical Science
III. INQUIRE Is There a Model To Explain Differences Between
Solids, Liquids, and Gases?
MATERIALS:
III-A. Searching for Evidence of Tiny
Particles
For each group of 3-4 teachers
• large round balloon
• almond or vanilla extract
• beaker or clear container of water
• sugar (individual restaurant packs are
recommended)
• stirring rod
For workshop leader demonstration:
• clear glass or plastic tube with end caps
(1-3 cm diameter, at least 50 cm long)
• isopropyl alcohol
• graduated cylinder for measuring above
liquids
• meter stick or metric tape
III-B. Making Inferences about Particles in
Solids, Liquids & Gases
Station 1 - Water
• hot plate on LOW setting
• pan of water
• bowl of ice
• tongs
• flask capped w/rubber stopper into
which glass tube has been inserted
• colored water
• glass marker
NOTE: Flask should contain enough
colored water to partially fill the glass tube.
Station 3 - Syringes
• 3 plastic syringes (100 cm3 capacity or
greater)
• epoxy
• sand
• water
NOTE: The three syringes should be halffilled with sand, water, and air and the ends
should be sealed with epoxy. For the air
syringe, depress the plunger half-way and
seal. The plungers in the sand and water
syringes should be pressed down to the
material with no air left and sealed.
Station 4 - Air Freshener
• solid air freshener with adjustable
container
NOTE: Remind participants to close after
use.
Station 5 - Blocks
• blocks that have the same dimensions
but made of different materials like:
iron, wood, Styrofoam ® ,and brick
• balance
• metric ruler
Station 6 - Colored Water
• food coloring
• dropper
• large container of water (1000 ml
beaker)
• several empty small beakers or clear
plastic cups
• Optional: chilled food coloring
Station 2 - Wire
• 0.5 m lengths of copper wire, about 32
gauge
• meter stick
• ring stand
• clamp to attach ring stand to table
• weight hanger
• slotted masses (100g - 500g)
For workshop leader:
• transparency of “A Particle Model of
Matter” (See page 78.)
• overhead projector
For each group:
• poster or chart paper
• markers
NOTE: 32 gauge copper wire should
require a force of about 20 N to break
III-D. Apply - None
August, 2000
III-C. Make Sense - None
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Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
A. Searching for Evidence of Tiny Particles
It is recommended that you introduce this
activity by saying that you assume the
teachers have all learned at some time in
their formal education that matter is
made of tiny particles called atoms and
molecules, and that for the remainder of
the workshop these will simply be
referred to as “particles” of matter. Ask
participants to share what they know
about the size of such particles. More
importantly, ask them how they know
that matter is made of tiny particles.
Can they provide everyday examples? In
other words, can they supply Evidence?
(Many teachers cannot.) Tell the
teachers that, through this series of miniactivities, you want to help them find
evidence to support the idea that matter
is not continuous, but is made of tiny
discrete particles.
NOTE: Parts or all of this activity can be done as
demonstrations from the front of the room.
III-A. Searching for Evidence of Tiny Particles
1. Look at a color newspaper or
magazine picture with your naked eye.
Then observe it again through a very
strong magnifying glass or a handheld microscope. What do you see?
2. Place several drops of vanilla or
almond extract into a clean balloon. Be
very careful not to get any of the extract
on the outside of the balloon.
3. Add sugar to a beaker of water and stir
until completely dissolved. How does this
provide evidence that matter is made of
tiny particles? Discuss ideas in your
group.
4. Prepare to make some quantitative
observations as your workshop leader
mixes sugar and water together in the
front of the room. Record measurements
in the chart below.
Volume (ml)
Vanilla/ Almond Extract
Mass (g)
Sugar
Balloon
Water
Take time to discuss the difference
between observation (that which can be
visibly discerned or detected through the
use of the five senses) and inference (that
which is not directly observable but
which is logically deduced from
observations). You might point out that
science makes a clear distinction
between observation and inference, but
making these distinctions requires
thought and practice. As teachers
progress through each of the activities
below, encourage them to discuss and try
to distinguish between their observations
and inferences.
August, 2000
Sugar + Water
Carefully inflate the balloon and tie it.
Can you smell the extract on the outside
of the balloon? What are your
explanations for what you notice? What
evidence does this demonstration provide
that matter is made of tiny particles?
Discuss your ideas with other members of
your small group before writing down
what you think.
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Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
A. Searching for Evidence of Tiny Particles (cont.)
When everyone is through, have a roundup discussion for different groups to
share their ideas. Try to draw out the
following ideas, if they are not advanced
by the groups:
1)The fact that you can smell the extract
means that it was able to pass through
the balloon and travel through the air
and into your nostrils.
2) If the extract was able to pass through
the balloon wall, then the balloon
material must have some spaces through
which the extract could pass. These
spaces must be fairly small since you
cannot see them.
3) The only way the extract can pass
through the empty spaces in the balloon
is if it is made of particles that are even
smaller in diameter than the empty
spaces in the balloon material.
III-A. Searching for Evidence of Tiny Particles
1. Look at a color newspaper or
magazine picture with your naked eye.
Then observe it again through a very
strong magnifying glass or a handheld microscope. What do you see?
2. Place several drops of vanilla or
almond extract into a clean balloon. Be
very careful not to get any of the extract
on the outside of the balloon.
3. Add sugar to a beaker of water and stir
until completely dissolved. How does this
provide evidence that matter is made of
tiny particles? Discuss ideas in your
group.
4. Prepare to make some quantitati ve
observations as your workshop leader
mixes sugar and water together in the
front of the room. Record measurements
in the chart below.
Volume (ml)
Vanilla/ Almond Extract
Mass (g)
Sugar
Balloon
Water
Sugar + Water
4) You could not see the extract as it
passed through the air to your nose
which is evidence that the extract must
be composed of particles or pieces that
are too small to be perceived by the
human eye.
Carefully inflate the balloon and tie it.
Can you smell the extract on the outside
of the balloon? What are your
explanations for what you notice? What
evidence does this demonstration provide
that matter is made of tiny particles?
Discuss your ideas with other members of
your small group before writing down
what you think.
5) The particles of extract were in
motion.
August, 2000
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Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
A. Searching for Evidence of Tiny Particles (cont.)
When participants initially look at the
picture, they will see areas of solid ,
continuous color. When they look at
the picture through the magnifier,
they will see that each colored area is
actually made of tiny dots of color.
Use this as an analogy to discuss the
idea that, while something may
appear to be continuous, it may
actually be comprised of smaller
individual pieces.
III-A. Searching for Evidence of Tiny Particles
1. Look at a color newspaper or
magazine picture with your naked eye.
Then observe it again through a very
strong magnifying glass or a handheld microscope. What do you see?
Participants should recognize that while
the sugar can no longer be seen, it is still
there, as evidenced by the sweetness of
the water. (If participants seem
skeptical, ask them for a way to find out
whether the sugar is still there. Someone
should suggest heating the water to let it
evaporate. You may choose to actually
do this.) The uniformly sweet taste of the
water is evidence that there are empty
spaces uniformly distributed throughout
the water. The invisibility of the sugar is
evidence that the sugar must be made of
very small particles, because if they were
larger we could see them. You may want
to show that the sugar particles in the
water are too small to be seen even by a
microscope.
This demonstration works best when
two large graduated cylinder (250 mL
or larger) are used. Place 200 mL of
water in one cylinder and 50 mL of
sugar in the other. Mass each on an
electronic balance. Then pour the
August, 2000
2. Place several drops of vanilla or
almond extract into a clean balloon. Be
very careful not to get any of the extract
on the outside of the balloon.
3. Add sugar to a beaker of water and stir
until completely dissolved. How does this
provide evidence that matter is made of
tiny particles? Discuss ideas in your
group.
4. Prepare to make some quantitative
observations as your workshop leader
mixes sugar and water together in the
front of the room. Record measurements
in the chart below.
Volume (ml)
Vanilla/ Almond Extract
Mass (g)
Sugar
Balloon
Water
Sugar + Water
Carefully inflate the balloon and tie it.
Can you smell the extract on the outside
of the balloon? What are your
explanations for what you notice? What
evidence does this demonstration provide
that matter is made of tiny particles?
Discuss your ideas with other members of
your small group before writing down
what you think.
sugar into the water and stir until most of the sugar is
dissolved. Read the new volume and measure the combined mass
© OPPS - Louisiana State University
32
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
ADVANCE PREPARATION
In this activity, participants rotate through a series of stations that cover a range of properties
and behaviors of solids, liquids, and gases. You may design your own stations to add to or
replace the ones included here. It is recommended that you set up enough stations for
participants to work in pairs. For a workshop of 24:
Activity
Water
Wire
Blocks
Syringes
Air Freshener
Colored Water
Property
Expansion/Contraction
Tensile Strength
Density
Compressibility
Change of State/Diffusion
Diffusion
Number of Stations
2
2
2
2
2
2
Inform participants that they will rotate through stations in this activity to observe a variety
of phenomena involving solids, liquids, and gases. Tell them that at each station they should
talk with their partner to try to make sense of what is happening in terms of the particles of
matter. Suggest that they may want to draw diagrams to help clarify their ideas. Ask
participants to return materials to their original condition before leaving each station. Allow
about 10 minutes at each station - 3 minutes for the activity itself, and 7 minutes for
discussion and writing.
August, 2000
© OPPS - Louisiana State University
33
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Advance Preparation: It is important to completely fill the flask with colored water, leaving no air
space in the flask.
Station 1
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
You may want to clarify that the liquid
contains at least two different kinds of
particles — the particles of food coloring
as well as the particles of water.
STATION 1 - WATER
1. Notice the level of the colored water in
the flask with the glass tube.
2. What do you think is happening to the
water particles that might explain your
observations? Try to draw a picture of
the “particle model.”
3. Would you draw the same kind of
picture to explain how a thermometer
works?
What happens when you set the flask in
the bowl of ice? What happens when you
set the flask in a pan of water on the hot
plate?
August, 2000
© OPPS - Louisiana State University
34
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Advance Preparation : Clamp a ring stand or other support to the tabletop. Attach a length of thin
copper wire (about 32-gauge) to the ring so that it hangs vertically. Attach a weight hanger to the
lower end of the wire. Have slotted masses (100-500g) available for teachers to add to the weight
hanger. Have additional lengths of copper available for other groups to use.
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
Station 2
STATION 2 - WIRE
Be on the lookout for “particle pictures”
that show the size of the particles
increasing as the wire is stretched. This
indicates a misconception that needs to
be addressed.
1. What happens when you and a partner
add weights to the hanging copper wire?
2. From your observations, what can you
infer about the particles of copper that
compose the wire? Try to draw a picture
of the “particle model” to illustrate your
ideas.
Copper Wire
Teachers may not be able to detect a
measurable increase in the length of the
copper wire, but should note that after a
certain amount of weight is hung from it,
it will snap.
August, 2000
Weight Hanger
© OPPS - Louisiana State University
35
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Station 3
There is more than one “particle
picture” that teachers might draw to
account for their observations. Teachers
may show the more massive block as
having more particles and/or as having
heavier particles.
August, 2000
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
STATION 3 - BLOCKS
1. Examine the two blocks. How do their
volumes compare? Their masses?
© OPPS - Louisiana State University
2. How can you explain your
observations in terms of the particles of
which each block is composed? Try to
draw a picture of the “particle model” that
can account for your observations.
36
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Station 4
The water and sand are essentially
noncompressible. The air can be
compressed. Be on the lookout for
pictures that show the size of the
particles changing rather that the space
between them changing.
August, 2000
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
STATION 4 - SYRINGES
1. Observe the three syringes. One is
filled with sand, one with water, and one
with air. Try to compress the contents of
each syringe. What do you find?
© OPPS - Louisiana State University
2. Based upon your observations, what
can you infer about the particles of sand,
water, and air? Try to draw a picture of
the “particle model” that can account for
your observations.
37
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Station 5
During the follow-up discussion, point
out that the reason you can smell the
freshener is that some particles from the
freshener actually enter your nose. Some
of the solid freshener sublimed (became
a gas). Discuss that the particles of
freshener diffuse through the air
because of the concentration gradient —
fluid particles move from an area of
higher concentration to an area of lower
concentration.
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
STATION 5 - AIR FRESHENER
1. What do you notice as you open, then
close, the vents on the solid room
freshener?
2. Try to explain your observations in
terms of what is happening to the
particles of the solid freshener. Draw a
picture of the “particle model” to illustrate
your ideas.
Air Freshener
August, 2000
© OPPS - Louisiana State University
38
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Station 6
Both the food coloring and the water
should be at room temperature.
III-B. Making Inferences about Particles in Solids, Liquids,
and Gases
STATION 6 - COLORED WATER
1. Place some fresh water in a small cup
or beaker. Add a couple of drops of food
coloring. Do not stir. What do you see
happening?
2. What can you infer about the particles
of food coloring and the particles of
water? Draw a picture of the “particle
model” to illustrate your ideas.
This optional step requires that two
bottles of food coloring (same color) be
supplied, with one set in a small bowl of
ice. When the chilled food coloring is
added to the water, it sinks to the bottom
of the cup or beaker.
OPTIONAL: Add a couple of drops of
chilled food coloring to some fresh water.
August, 2000
© OPPS - Louisiana State University
39
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Activity Follow-up
As pairs of participants complete the rotation of stations, direct them to form discussion
groups of four me mbers. Give each group responsibility for considering one of the activities
in detail.
Members of the discussion groups might be asked to
·
·
·
·
Review their own ideas relating to the activity (refer back to personal activity sheets).
Relate their ideas to other members of the group ;
Discuss the relative merits of the proposed ideas;
Reach a consensus over what appears to be the “best explanation” for the activity.
Poster Production
Give each group a piece of poster or chart paper and some large pens and ask them to
summarize the consensus view of the group relating to their assigned activity. Encourage
them to draw and label a picture showing what they think is happening in terms of particles
that might account for their observations.
Posters provide a permanent record (a paper memory) of the participant ideas that exist at
this point in the workshop -- prior to any formal input by the workshop leader. The posters
can be referred to as the workshop proceeds; used in this manner they provide a baseline
against which the development of participant ideas can be monitored.
It may be worthwhile to point out that the posters represent the views of the group at this
point in time and, like the ideas of scientists, these views may change.
When the posters are complete, they should be placed upon a wall and each group asked to
say a little bit about their ideas as shown on the poster. Concern or embarrassment about
displaying posters that may not be scientifically correct can be overcome by making a large
title poster, e.g. “Our Ideas at 10:00 am on March 23.”
August, 2000
© OPPS - Louisiana State University
40
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Activity Follow-up (Cont.)
Using Standard Notation to Represent Particles
At some point — either now or after the next major activity — participants may find a need to
standardize particle notation. Participants can provide ideas for how this might be done by
suggesting ways for showing differences in the mass of particles, in the size of particles, and/or
the motion of particles. As workshop leader, you may need to solicit ideas as to whether there
needs to be a way for clarifying the “state” of particles: solid, liquid, or gas. This may be a
good opportunity to bring out the idea that the particles themselves do not change as a
substance undergoes a change in physical state.
You may want to use this opportunity to take time to talk about the importance of standardized
language and notation in science.
A Particle Model for Matter
Have participants reflect on the collection of posters (and the activities they represent) and
make a list of what they reveal about the particles: 1) in solids, 2) in liquids, and 3) in gases.
Give teachers time to discuss their ideas in small groups, then hold a round-up discussion for
participants to share their ideas. Post these in a three-column format for all to see:
SOLIDS
1.
2.
etc.
LIQUIDS
1.
2.
GASES
1.
2.
As each item is posted, ask participants to identify whether it is based on observation or
inference. Discuss why this difference is important in formulating a scientific model or theory.
Expect that the participants will come up with some (and possibly most) of the the basic
elements of the particle model. This is an appropriate point to formally introduce the particle
model. Show the “A Particle Model of Matter” transparency (See page 78). Ask participants
“What evidence from the activities we have done today or from your own experiences supports
this model?” Discuss how a good model should account for observations and enable
predictions to be made. Encourage participants to volunteer examples of how the particle model
meets these two criteria.
August, 2000
© OPPS - Louisiana State University
41
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Activity Follow-up (Cont.)
In developing the particle model, be aware that some participants probably harbor one or more
commonly held alternative particle ideas, and these ideas are not easily abandoned. They
include the following:
•
Confusion about the nature of the particles themselves. Many people have trouble
appreciating the shape and size of particles. In some cases, there is confusion between
particles of matter and biological cells, a confusion that is increased by the use of the
word “nucleus.” The word itself can also cause confusion, with atoms and molecules
envisioned as being similar to particles of sand or sugar.
•
Attributing macroscopic properties to particles. People use everyday experiences to
interpret ways in which individual particles behave, often attributing bulk properties
such as melting, expanding, floating, and even exp loding to an individual particle.
•
Confusion about the motion of particles. Commonly held notions include
- Particles only mo ve when they are heated;
- Particles stop moving at 0oC.;
- Air particles always move upward.
•
Confusion about forces/bonding between particles. Many people have difficulty in
distinguishing forces between different particles (intermolecular forces) and bonding
within a particle (intramolecular forces). NOTE: This workshop only addresses the
former.
•
Confusion about what is in the space between particles. People feel very uncomfortable
with the idea that a vacuum exists between particles, especially when they think about
solids and liquids. People commonly think that air is filling the gaps.
•
Attributing anthropomorphic properties to particles. Children, especially, may believe
that particles are “alive.”
August, 2000
© OPPS - Louisiana State University
42
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
B. Making Inferences about Particles in Solids, Liquids, and Gases
Activity Follow-up (Cont.)
By the end of the discussion, participants should
•
recognize that ALL substances (and not just scientific ones) are made of particles
(called atoms or molecules);
•
be able to visualize solids, liquids, and gases in terms of the
- spatial arrangement of their particles
- motion of the particles
- temperature effects leading to changes of state
•
be prepared to explain simple phenomena in terms of particles.
Poster Revision
Give participants the opportunity to revise their posters in light of the particle model.
August, 2000
© OPPS - Louisiana State University
43
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
C. Make Sense
Remember that the basic purpose of the Make sense activity is to reach closure on the ideas developed
during the Inquire, and to see how these new ideas fit together with those already developed.
Provide additional poster/chart paper if
needed. Expect that some groups may be
reluctant to make changes to their
poster; these groups may require
special attention.
III-C. Make Sense
1. Discuss with your group how you
might want to revise your poster based on
the discussion of the particle model.
Make any agreed upon changes at this
time and then display your poster for
other groups to see.
3. Revisit your list of “Questions About
Solids, Liquids, and Gases.” Mark
through the questions that you can now
answer. Add any new questions that
have arisen.
Conduct a round-up discussion for
groups to share the changes they have
made. This is also an opportunity for
you to clarify any misunderstandings
that may have surfaced and to reach
closure on the basic particle model.
OPPS field tests have shown that
providing participants with time to
review and modify their list of science
ideas is a critical step in the workshop.
Do NOT skip or shortchange it. The
reason it is important for groups to write
their ideas in complete sentences is that
an incomplete sentence represents an
incomplete idea. You may want to have
groups, in turn, share the changes they
have made, or you may want to have
them simply post their lists for all to
view. It is very important that you
carefully scrutinize these lists, for they
often reveal misunderstandings or
incomplete ideas which you need to
address. Even more revealing are ideas
that are obviously missing from a list.
This is a red flag that a group does not
feel comfortable enough about their
understanding of the idea to express it
clearly. Use your judgment on how to
proceed.
August, 2000
2. Get your group’s list of “Ideas About
Solids, Liquids, and Gases.” Have any of
your ideas changed? Do you need to add
any new ideas? Make these changes
and additions to your list. Make sure that
all ideas are expressed in complete
sentences.
Possible approaches:
additional activities or demonstrations, coupled with
“make sense” discussions
•
simple explanations with concrete examples
•
Socratic dialogue
•
peer explanations (teachers who have grasped the idea
explain it to those who have not)
•
© OPPS - Louisiana State University
44
Operation Primary Physical Science
III. INQUIRE Is There a Model to Explain Differences Between
Solids, Liquids, and Gases?
D. Apply
These questions require the participants
to think about solids, liquids, and gases
in terms of the particles of which they
are composed. The questions let both you
and the participants take stock of the
degree to which they understand the
particle model presented. Use these
questions as an opportunity to discuss
and clarify any confusion that may exist.
III-D. Apply
1. The drawing below shows a closed
flask containing air. Imagine you can see
the particles of air in the flask. Draw in
the flask how the particles would look.
2. Rosalind’s science teacher asked her
to draw out a PARTICLE diagram of
water. This is what Rosalind drew:
Water Particle
Air
Air
What do you think of Rosalind’s drawing?
Some participants may show the
remaining air particles gathered near the
lower portion of the flask. Be sure to
address this misconception.
The flask is connected to a pump and
some of the air is taken out.
Draw and label an appropriate PARTICLE
diagram of liquid water for Rosalind.
This is the flask after some of the air is
taken out. Notice that the flask has been
closed. Draw how the inside of the flask
would look now.
August, 2000
© OPPS - Louisiana State University
45
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
GOAL:
For teachers to recognize, compare and, in
some cases, be able to measure, some of the
diverse properties of solids, liquids and gases.
OVERVIEW:
Teachers will investigate the properties of solids,
then liquids, then gases. As they discover
properties, they will try to make sense of them in
terms of the particle model. Teachers will apply
what they have learned by analyzing and
evaluating different brands or kinds of a grocery
store product in terms of desirable properties.
IV-A. Investigating the Properties of Solids
Given an assortment of solids, as well as other
materials and tools, teachers generate and discuss
testable questions they might try to answer about
the properties of solids. Each group of teachers
selects one question to investigate about solids,
designs and conducts an investigation to answer
the question, then presents what they did and what
they found out. These initial investigations of
solids may lead to further investigations.
Discussions , which accompany the investigations,
help teachers to develop clear definitions —
consistent with those of the scientific
community — of properties such as hardness,
elasticity, tensile strength, malleability,
absorbency, etc., and simple procedures for
quantitatively comparing solids in terms of these
properties. At the end of the activity, teachers
consider how the particle model can be used to
explain some of the similarities and differences in
the properties of solids that they observed.
(Teachers should be informed that this simple
model is not sufficient to explain all of their
observations; many properties are determined by
additional factors, such as the size of the
particles, the way electrons are distributed in
particles that are atoms, the way atoms are
arranged in particles that are molecules, etc.)
August, 2000
IV-B. Investigating the Properties of Liquids
Teachers use the materials and tools provided to
freely explore the properties of three different
clear liquids: water, isopropyl alcohol, and
glycerin (or mineral oil). When teachers have
finished exploring, they discuss similarities and
differences in the properties of liquids. This
includes a discussion of cohesion, adhesion,
surface tension, viscosity, and rate of evaporation.
If time permits, each group may select one
property to further explore. At the end of the
activity, teachers consider how the particle model
can be used to explain some of the similarities and
differences in the properties of liquids that they
observed.
IV-C. Investigating the Properties of Gases
A series of demonstrations show that gases are
fluids, exert pressure, have a very small mass
for the amount of volume they occupy, can be
compressed, and diffuse rapidly. After viewing
and discussing the demonstrations, teachers
consider how the particle model can be used to
explain some of the similarities and differences
in the properties of gases that they observed.
IV-D. Make Sense
Teachers are given the opportunity to reflect on
and make sense of what they have learned
during the inquiry. They also add to and/or
modify their list of “Ideas about Solids,
Liquids, and Gases” and revisit their list of
“Questions about Solids, Liquids, and Gases.”
IV-E. Apply
In this paper and pencil exercise, teachers list
the properties that are desirable in a clear,
plastic food wrap. They then design a test that
can be used to compare different brands of
food wrap in terms of one selected property.
© OPPS - Louisiana State University
46
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
SCIENCE IDEAS
•
•
•
•
Solids vary in properties such as
hardness, crystalline structure,
malleability, conductivity.
Liquids vary in properties such as
cohesion, adhesion, surface tension,
viscosity, rate of evaporation, etc.
Gases exert pressure, have a very
small mass for their volume, can be
compressed, diffuse rapidly, and move
from areas of higher pressure to areas
of lower pressure.
The collective properties of a material
determine its suitability for a particular
use.
August, 2000
© OPPS - Louisiana State University
47
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
MATERIALS:
IV-A. Investigating the Properties of Solids
Assign one of the following sets to each group:
•
4 different minerals — samples such as quartz, feldspar, talc, calcite, gypsum, etc.
•
4 different woods — blocks or strips of ash, pine, balsa, cedar, etc.
•
4 different white papers — poster paper, blotter paper, paper towel, copy paper. etc.
•
4 different metals — strips of copper, aluminum, lead, zinc, etc.
•
4 different cloths — squares of cotton, rayon, polyester knit, nylon, chamois, rubber
sheeting, etc. (include samples that will stretch)
•
4 different threads/wires of almost identical diameters — cotton, nylon, fishing line,
thin copper wire, etc.
At a central table:
balances
metric rulers
support stands
hooked weights
beakers
couple of nails
tennis ball
scissors
masking tape
porcelain streak plates
embroidery hoop
wax paper
pennies
vinegar
diluted hydrochloric acid
isopropyl alcohol
thumbtack
IV-B. Investigating the Properties of Liquids
For each group:
•
water*
•
glycerin* (or a clear, colorless oil)
•
isopropyl (rubbing) alcohol*
•
small containers for the liquids (such as clear plastic cups)
•
kosher salt
•
sugar
•
3 dropper pipettes (one for each liquid)
•
food coloring (any color)
•
waxed paper
•
wooden or plastic stirrers (coffee stirrers will work)
•
paper towels
•
notebook or copy paper
* It is convenient if liquids can be provided in dropper bottles.
NOTE: You may want to place all materials at a central station — with the possible exception of the three liquids — for participants to pick up as needed.
August, 2000
© OPPS - Louisiana State University
48
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
MATERIALS:
IV-C. Investigating the Properties of Gases
Part One - Blow Up a Teacher! (demo)
For whole group:
• 10 strong gallon-size Ziploc ® bags
• 1 heavyweight 30 gallon trash bag
• 10 drinking straws
•
flexible adhesive tape
•
2 lightweight tables (stable and strong)
Part Two - A New Way to Inflate a Balloon (demo)
For whole group:
•
small piece of dry ice
•
tongs and mitts for handling dry ice
•
large oblong balloon
•
1000 ml graduated cylinder (optional)
Part Three - Strawberry Gas (demo)
•
petri dish
•
strawberry gelatin powder (Jell-O® )
•
water
•
stirrer
•
overhead projector and screen
Part Four - Bottle Blowing (demo)
•
clear soda bottle (16 oz or half-liter)
•
small wad of paper
Part Five - Comparing Gases
•
air pump
•
helium tank
* The need for bottles of gas, and the
•
carbon dioxide cartridge or other source
number of bottles of each needed,
depends on whether this is done as a
•
bottles of air, helium and carbon dioxide*
demonstration or in small groups (see
•
birthday candles
activity sheet).
•
matches or lighter
•
bubble solution with bubble blower
•
balloons (optional)
•
aquarium tank
•
dry ice
IV-D. Making Sense
None
IV-E. Applying
None
August, 2000
© OPPS - Louisiana State University
49
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
A. Investigating the Properties of Solids
Distribute a different set of solids to each
group, or let groups select their own set
from the central table. Let groups know
what materials are available at the
central table.
IV-A. Investigating the Properties of Solids
Take time to discuss, or to remind the
participants if they have discussed it
before, of what is meant by a “testable”
question. You may point out that a
question that might be testable to a
scientist who has the appropriate tools
and equipment, may not be able to be
tested within the limited time and
resources available in the workshop.
Be sure to write up all the questions
groups have to offer on a flip chart,
overhead transparency, or board. Try to
avoid duplication. As you post questions
on this overall list, have participants
discuss the “testability” of each.
1. Examine your group’s solids. Discuss
what kinds of questions you could ask
about the solids using your observations
and the materials available. Make a list of
these questions.
3. Choose several of the questions from
the overall list for your group to focus on.
Design a number of experiments (fair
tests) that might provide answers.
2. Share your list of questions with those
of other groups in a whole-group
discussion.
4. Make a presentation of your
observations and results to all other
groups. Be sure to explain the answers
your investigations have revealed.
You might want to discuss the idea of a
“fair test” before teachers begin to
design their experiments.
As each group presents, ask all groups to
reflect on what the group did and what
they found out. Ask groups to consider
the “fairness” of the tests and
experiments conducted. How reliable are
the results? How could tests be improved
or extended to make them more reliable?
What other solids could they test using
the same methods?
August, 2000
© OPPS - Louisiana State University
50
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
A. Investigating the Properties of Solids
Activity Follow-up
Properties of Solids
In a large group discussion, have participants make a list of all the differing properties of solids
revealed through their investigations. Let them add properties they recognized but did not
investigate. They may need your help in labeling the properties as scientists would. Help them
develop a clear definition or description of each property, and at least one way of quantitatively
or qualitatively comparing solids in terms of the property. You may want to add properties that
the participants did not think of. Properties on the list might include hardness, tensile strength,
elasticity, solubility, absorbency, porosity, electrical conductivity, and magnetism.
Revisiting the Particle Model
Get teachers to cons ider what their investigations revealed about the particle nature of matter.
Did their observations provide any evidence to fur ther support the particle model? Can they
explain any of the properties they studied in terms of what is happening to particles of matter?
(They will not be able to do this for all properties. The particle explanation for certain
properties is beyond the scope of this workshop.)
Doing Science
Close the session by having participants reflect on the nature of the activity they just completed.
How is it different from most of the science “experiments” they conducted when they were in
school? In what ways is it more like the work of scientists? Have them discuss the importance
of
•
making observations
•
asking scientific questions
•
devising experiments and fair tests to investigate these questions
•
recording and reviewing results in order to determine reasonable answers
NOTE: Participants should have conducted an “Elements of Inquiry” activity —either
“Petals Around the Rose” or “Queen Anne ” — as part of their introduction to the OPPS
program. You might have participants contrast this activity to the introductory inquiry
activity they conducted earlier. The intent of this discussion is to reinforce the value of doing
inquiry science in the classroom.
August, 2000
© OPPS - Louisiana State University
51
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
B. Investigating the Properties of Liquids
Provide each group with a set of
materials.
As groups work, walk around and check that each of the
questions is being addressed by at least one group.
It is probably best to lead this step as a
whole group activity. Be sure to write up
all the questions groups have to offer on
a flip chart, overhead transparency, or
board. Try to avoid duplication. Check
the list of questions below, and draw
attention to any that groups might have
missed. Add these to the list also.
— Can you tell liquids apart by feel?
Smell? (Safety: DO NOT TASTE)
IV-B. Investigating the Properties of Liquids
1. Examine your group’s materials.
Discuss what kinds of questions you
could ask about the three liquids using
the materials available. Make a list of
these questions.
3. Choose several questions from the
overall list for your group to focus on.
Design a number of experiments, or fair
tests, that might provide answers.
Again, reinforce the notion of a “testable”
questions.
— Do the liquids behave in the same way
when you add food coloring to them?
— Do the liquids look (or behave) the
same way when you place drops of
them on waxed paper? Notebook
paper?
2. Compare your list of questions to
those that the other groups have come up
with. Make an “overall” list.
4. Make a presentation of your
observations and results to all the other
groups. Be sure to explain the answers
your investigations have revealed.
— Do the liquids behave the same way
when you race drops of them down a
slanted piece of wax paper?
— Do the liquids behave the same way
when you add salt to them? Sugar?
— How do the liquids pour?
— Which liquids are the runniest?
— What about absorption by paper
towels?
— Do they all have the same rate of
evaporation?
— What happens if you drop a marble or
other small object through each liq uid?
August, 2000
© OPPS - Louisiana State University
52
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
B. Investigating the Properties of Liquids
Activity Follow-up
Properties of Liquids
Ask each group to reflect on what all of the groups did and what they found out as they tried to
answer the questions generated about the three liquids. Have them list any generalizations they
feel they can make about the 3 liquids, or about liquids in general.
Hold a “round-up” discussion and note the ideas that groups offer.
Consolidate this by listing all of the properties of liquids that groups feel have been discovered.
Write these on chart paper, overhead, or blackboard for all to see. Add to the list other
properties that the groups can identify. They may need your help in labeling these properties as
scientists would. Help them develop a clear definition or description of each property, and at
least one way of measuring or comparing liquids in terms of the property. Properties on the list
might include cohesion, adhesion, sur face tension, solubility/miscibility, viscosity, rate of
evaporation.
NOTE: See the KEY IDEAS sheet for definitions and descrip tions of liquid properties.
Revisiting the Particle Model
Get teachers to consider what their investigations may have revealed about the particle nature of
matter. Did their observations provide any evidence to further support the particle model? Can
they explain any of the properties they studied in terms of what is happening to particles of
matter? (They will not be able to do this for all properties. The particle explanation for certain
properties is beyond the scope of this workshop.)
Doing Science
Close the session by having participants reflect on the nature of the activity they just completed.
Have them discuss the importance of
•
•
•
•
August, 2000
making observations
asking scientific questions
devising experiments and fair tests to investigate these questions
recording and reviewing results in order to determine reasonable answers
© OPPS - Louisiana State University
53
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
B. Investigating the Properties of Liquids
Activity Follow-up (Cont.)
OPTIONAL: BEHAVIOR OF LIQUIDS IN DIFFERENT CONTAINERS
You may want to demonstrate—or have the teachers explore and discover—how water or
other liquids behave when placed in a variety of containers made of tubes, cups, and bottles.
A full page transparency master of the above diagram is included at the end of this module.
(See page 79.)
Make a list of the properties of liquids that teachers may identify from the activity:
•
•
•
•
Liquids take the shape of their container.
Liquids find their own level.
Liquids flow “downhill” and do not flow “uphill”.
Liquids are affected by gravity and air pressure.
August, 2000
© OPPS - Louisiana State University
54
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases
PART ONE: Blow Up a Teacher
This demonstration shows that a gas
can exert tremendous pressure on
surfaces with which it comes in
contact.
IV-C. Investigating the Properties of Gases
PART ONE: Blow Up a Teacher!
(Demonstration)
Draw out the idea that the
demonstration shows that a gas can
push, or exert pressure, on things.
Gas particles moving very rapidly
through space collide many times
each second with other gas particles
and with the particles that comprise
the inside surface of the solid plastic
bag. Thus, every square inch of the
inside of the bag is being constantly
bombarded by tiny particles of gas
that push the surfaces of the bag
outward and cause it to inflate. You
may want to point out how air inside
the tires similarly lifts your car.
There are several other very simple
and well known air pressure
demonstrations that you can use
instead of, or in addition to, this one.
Use the ease with which the
participants relate the phenomena to
the particle model as a gauge to see if
additional demonstrations are needed
in this part of the activity. Feel free to
use ones of your own or ones
suggested on the next page.
August, 2000
1. Observe a colleague being lifted by
air. Here is how it’s done:
Step 1: Assemble 6 inflatable plastic
bags.
Step 3: Place the assembly flat on a
table and then place a large
sheet of plywood, or another
stable (lightweight) upturned
table, on top.
drinking
straws
sticking
out of
sides
trash bag with inflatable bags
inside sandwiched between table
Step 4: Check for safety and then have
the designated teacher sit on the
board (or upturned table) while
other inflate their bags by
breathing into them.
Step 2: Place the six bags inside a
large plastic bag with straws
sticking out through the sides.
heavy
weight
trash bag
with
inflatable
plastic
bags
inside
drinking straws sticking out
of sides
© OPPS - Louisiana State University
2. What does this demonstration reveal
about gases? Can you explain what is
happening in terms of particle model?
55
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART ONE: Blow Up a Teacher (Cont.)
Alternate Demonstration 1
Alternate Demonstration 2
A thin yardstick (such as those given out at
furniture stores) is laid on the table with about 6-8
inches extending over the edge of the table. An
open sheet of news paper is laid flat over the
tabletop and covers the part of the yardstick that
rests on the table.
Fill a glass completely with water. Carefully cover
the glass by sliding a cardboard square over th e
top. Try not to let any air bubbles get trapped in
the glass. Hold the cardboard on the glass, invert
the glass, and then le t go of the cardboard. The
cardboard should stay put, held in place by the
pressure of the air. Slowly turn the glass sideways
to show that air exerts pressure in all directions.
A swift blow with your hand to the extended
yardstick causes the yardstick to snap. The
extended piece breaks off and falls to the floor.
The length of yardstick under the sheet of
newspaper moves barely, if at all, since it is held
in place by air pressing down on the sheet of
newspaper.
Encourage teachers to think about the air above
the newspaper, using their imagination to envision
tiny particles of air, zipping rapidly in all
directions, colliding frequently with one another
and with the surface of the newspaper. It is this
constant bombardment that holds the newspaper
flat on the table .
August, 2000
Ask participants to consider and discuss whether
this is consistent with the particle model for gases.
You can repeat the demonstration, covering the
glass with a piece of cheesecloth instead of
cardboard. When the glass is inverted, the water
does not flow out, even though there are holes in
the cheesecloth. Ask participants what they might
infer about particles from this. Some participants
will probably infer that the particles of water are
larger than the holes in the cheesecloth.
Encourage them to think of evidence which might
discount this idea. Discuss how particles of water
are very strongly attracted to one another, and
this is why water has very strong surface tension
as well as why it does not drip or flow through the
holes in the cheesecloth. Of course, if the holes in
the cloth are too large, then the weight of the
water above a hole (gravity) is sufficient to
overcome the attraction of the neighboring
particles (surface tension), and the water will fall.
(It’s kind of like playing Red Rover in elementary
school ...a kid who is big and strong enough can
exert enough force to break through the line of
kids holding hands.)
© OPPS - Louisiana State University
56
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART TWO: A New Way to Inflate a Balloon
This demonstration provides convincing
evidence that particles take up much
more space as a gas than they do as a
solid (or liquid).
IV-C. Investigating the Properties of Gases
PART TWO: A New Way to Inflate a
Balloon (Demonstration)
Use tongs to place a small piece of dry
ice, about 1-2 cm3 in size, into a large,
uninflated, oblong balloon. Quickly tie
the neck of the balloon, being very
cautious in your handling. You should
wear mitts, although this makes it very
difficult to tie the balloon. Let everyone
watch as the balloon inflates on its own.
1. Watch as your workshop leader
demonstrates a novel method of inflating
a balloon. A piece of dry ice is placed in
an uninflated balloon, and the neck of the
balloon is tied shut. Record what
happens below.
Dry Ice
If you have a 1000 ml graduated
cylinder, as soon as you tie the balloon,
drop it into the cylinder and let it inflate.
The inflated balloon should almost fill
the cylinder. This helps teachers to see
that dry ice occupies about 1000 times
more space as a gas than it does as a
solid.
Hold a large group discussion and ask
for volunteers to share their drawings
and explanations. These should show
that the particles of dry ice are very close
together as a solid, and very far apart as
a gas. The number and size of the
particles should not change, just the
space between them. Reinforce the idea
that when a substance changes physical
state, there is no change in the
composition of the individual particles.
The particles have just gained energy
and move faster and further apart (or
vice versa).
August, 2000
2. By yourself, see if you can draw a
BEFORE and AFTER picture that
explains what is happening in terms of the
particles of the dry ice. When you are
satisfied with your drawing, share it with
other teachers in your group. Did you all
agree? If not, discuss your differing ideas
and try to come to some consensus.
Balloon
3. What does this demonstration reveal
about the properties of gases? Discuss
your ideas with other members of your
group.
Participants should conclude that a large volume of gas has
a very small mass. (Avoid saying “low density” unless you
are sure that all participants are comfortable with and
understand the density concept).
© OPPS - Louisiana State University
57
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART THREE: Strawberry Gas
This demonstration illustrates the rapid
diffusion of gases. Prepare a very
concentrated solution of dry strawberry
Jell-o in water. You will only need a
small amount. Place several large drops
in a petri dish that has been set on the
stage of an overhead projector that is
turned ON. The liquid should not
completely cover the bottom of the dish.
Teachers should be able to see the
outline of the red liquid on the viewing
screen.
IV-C. Investigating the Properties of Gases
PART THREE: Strawberry Gas
(Demonstration)
1. Some strawberry Jell-O powder is
mixed with water and placed on a petri
dish on the stage of an overhead
projector. Note your observations below.
2. What does this demonstration reveal
about gases?
Teachers should begin to smell the
strawberry odor and, at about the same
time, should notice that the amount of
red liquid in the Petri dish has gotten
smaller. Teachers sitting near the
overhead projector should notice the
smell before teachers who are sitting
farther away. You may want to have
teachers raise their hands as the notice
the smell, so that teachers can get a feel
of how quickly the strawberry gas is
diffusing through the air.
Diffusion - the spontaneous spreading
out of particles to fill a space uniformly.
Discuss how the strawberry gas particles
move from an area of greater
In a follow-up discussion, draw out the idea that the rapid
concentration to an area of lower
concentration, and this motion continues diffusion of the strawberry gas is evidence that gas particles
are moving very fast and in all directions.
until the gas particles are uniformly
distributed about the room.
August, 2000
© OPPS - Louisiana State University
58
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART FOUR: Bottle Blowing
This demonstration shows that gas moves
from an area of higher pressure to an
area of lower pressure. There are a
number of oth er fascinating
demonstrations that can be used to
illustrate this same principle. Feel free
to use one of them instead of the one
below or, if time permits, to conduct
them in addition to this one.
Allow teachers to discuss their
predictions and the reasons for them
before conducting the demonstration.
PART FOUR: Bottle Blowing
(Demonstration)
1. An empty soda bottle is placed on its
side, and a very small wad of paper is laid
in the neck. What do you think will
happen if someone blows into the neck of
the bottle? Why? Discuss your ideas
with other members of your group.
2. Observe what actually happens as
your workshop leader, or another teacher,
blows into the bottle. Can you explain
what happened? What property of gases
has just been demonstrated?
PARTICLE DIAGRAM
Conduct the demonstration by
blowing a large amount of air very
quickly into the neck of the bottle.
Teachers may be surprised to see the
paper wad fly out of the bottle. (Or
they may have expected the
unexpected!) Ask teachers to think
about what was happening in terms of
particles of gas and to draw a particle
diagram to help them make sense of
their observations. Give them a few
minutes to draw, then get them to
discuss their ideas within their group.
Circulate among the participants as
they draw and discuss, giving hints as
needed. Example: “Try drawing the
particles of air outside of the bottle.”
wad of paper
Hold a discussion for groups to share
their drawings and corresponding
explanations for the phenomena. Help
everyone to see that, before you blow
into the bottle, the concentration — or
spacing — of particles of gas (air) is the
same inside as outside the bottle.
August, 2000
IV-C. Investigating the Properties of Gases
When you blow into the bottle, you suddenly increase the
total number of gas particles inside the bottle. This
causes the gas particles inside the bottle to be more
crowded together than the gas particles outside. As a
result, the paper wad was bombarded more frequently by
particles from inside the bottle than from outside the
bottle, hence the paper was pushed outward.
© OPPS - Louisiana State University
59
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART FOUR: Bottle Blowing (Cont.)
Explain that scientists would say that
there is greater air (or gas) pressure
inside the bottle than outside the bottle.
Pressure = force/area. Inside the bottle,
a greater force is exerted by gas
particles on every square inch of the
inner surface of the bottle and paper
wad.
Through this discussion, develop the idea
that
Gases move from an area of higher
pressure to an area of lower pressure.
Stress to the teachers that the above is a
very important and powerful idea
because it explains such a large number
and variety of everyday phenomena.
IV-C. Investigating the Properties of Gases
PART FOUR: Bottle Blowing
(Demonstration)
1. An empty soda bottle is placed on its
side, and a very small wad of paper is laid
in the neck. What do you think will
happen if someone blows into the neck of
the bottle? Why? Discuss your ideas
with other members of your group.
2. Observe what actually happens as
your workshop leader, or another teacher,
blows into the bottle. Can you explain
what happened? What property of gases
has just been demonstrated?
PARTICLE DIAGRAM
wad of paper
Give several examples of this....the cork
shoots off the champagne bottle, air
rushes out of a balloon rocket, gases are
expelled from a real rocket, weather
conditions change as air in areas of high
pressure in the atmosphere moves
toward areas of low pressure, etc. You
might ask participants to think of other
examples.
OPTIONAL: Extend the discussion by
getting participants to ponder the effect
of temperature differences on gas
pressure. For example, how might the
results of the paper in the bottle
demonstration be different if warm
breath is blown into the bottle rather
than cool breath, assuming all other
aspects of the blowing are the same?
(Particles of gas in the warmer breath
will be moving faster, will collide more
frequently and harder, and will push the
wad of paper out with greater force.)
August, 2000
© OPPS - Louisiana State University
60
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
C. Investigating the Properties of Gases (Cont.)
PART FIVE: Comparing Gases
Instructions on the participant activity sheet have been written to allow flexibility in the way you
conduct the activity. The availability of each of the three gases and the kind(s) of containers you have
them in may determine how you do this.
AIR — Use an air pump to dispense air
through an attached tube.
CARBON DIOXIDE — Small
cartridges of carbon dioxide (used to
propel toy cars) can be purchased from
many hobby stores. Or you may generate
CO2 by mixing vinegar and baking soda
in a flask fitted with a stopper and tube.
HELIUM — Tanks of helium can be
rented, or small tanks purchased, at
almost all party goods stores. Attach
a tube to the tank nozzle.
IV-C. Investigating the Properties of Gases
PART FIVE: Comparing Gases
1. In this part of the activity, you will
examine differences between gases by
comparing the properties of three
common gases: air, carbon dioxide, and
helium.
Try blowing bubbles or inflating balloons
with each gas. What differences do you
notice between the different gases?
Record your observations.
3. From your collective observations,
what can you infer about the differences
between air, carbon dioxide, and helium?
In the spaces below, draw a particle
picture of each gas that would account for
these differences.
AIR
CARBON DIOXIDE
2. Watch as your workshop leader blows
bubbles filled with each gas into an
aquarium that contains a slab of dry ice in
the bottom. Record and try to make
sense of your observations.
You will also need a small slab of dry
ice which can be purchased at an ice
house, or sometimes a small amount
can be obtained from an ice cream
store.
Using tongs, place a slab or chunk of dry
ice in the bottom of an aquarium. Blow
bubbles of each gas into the aquarium.
HELIUM
dry ice
When teachers have completed this part
of the activity, have each group get
together with another nearby group to
compare their particle pictures and
explanations.
August, 2000
© OPPS - Louisiana State University
61
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
D. Make Sense
This is your opportunity to clear up any
misunderstandings that have surfaced, to
make connections between the various
properties of matter, and to reach
closure for this inquiry.
IV-D. Make Sense
1. Think back on the properties of solids,
liquids, and gases that you have
investigated in this inquiry. Which of
these can be explained in terms of the
particle model presented earlier in the
workshop? Share your ideas with your
group.
3. Revisit your list of “Questions about
Solids, Liquids, and Gases.” Mark
through the questions that you can now
answer. Add any new questions that
have arisen.
2. Get out your group’s list of “Ideas
about Solids, Liquids, and Gases.” Have
any of your ideas changed? Do you need
to add any new ideas?
August, 2000
© OPPS - Louisiana State University
62
Operation Primary Physical Science
IV. INQUIRE
What Can We Learn about Properties of Solids,
Liquids, and Gases?
E. Apply
Introduce the activity by informing
participants that they will now use what
they have learned about different
properties of matter to do two things :
1) Analyze a common household product
to determine what properties are
important in the product.
IV-E. Apply- Consumer Testing
1. You are going to the store to buy some
clear, plastic, food wrap. List five
desirable physical properties of food wrap
and/or the box it comes in. Explain WHY
each property is desirable.
2) Design a test to compare different
brands of a product in terms of one of its
desirable properties.
August, 2000
© OPPS - Louisiana State University
2. Select one of the properties above and
design an experiment you could do to
compare three different brands of food
wrap (Saran®, Handiwrap®, and Glad®)
in terms of this property. Describe your
procedure on the back of this page in
enough detail that a classmate could
conduct your experiment.
63
Operation Primary Physical Science
V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
GOAL:
To help participants develop an understanding of
the relationship between the mass and volume of a
substance (density), to have participants recognize
the importance of density, and to enable them to
use density to predict sinking and floating
behavior and to identify unknown matter.
OVERVIEW:
After having extensively examined properties of
solids, liquids, and gases, participants consider
whether some properties are more important, or
more useful, than others.
V-A. Common Properties of Solids, Liquids,
and Gases
Teachers work in groups to prepare a Venn
diagram that shows the properties of solids,
liquids, and gases. Diagrams are compared and
critiqued and the idea is developed that all forms
of matter — solids, liquids, and gases — have in
common the properties of mass and volume. The
definition of matter as “anything that has mass
and takes up space” is discussed in this light.
Everyday situations in which mass or volume is
used to describe the amount of matter (such as at
the grocery store), and ways of measuring mass
and volume, are also discussed.
V-B. Exploring Mass and Volume
Teachers investigate whether there is a relationship between mass and volume. Each group of
teachers is assigned a different kind of matter (a
solid that is insoluble in water or a liquid) to
investigate, such as aluminum foil, water, salt, oil,
Styrofoam®, or paper clips. No specific
instructions are given, but each group is supplied
with a balance, a metric ruler, one or more
graduated cylinders, and (optionally) an overflow
can. After about 20 minutes, groups take turns
sharing their procedures and findings. The
concept of density is developed, the densities of
the various materials used in the activity are
compared, and the idea that density, unlike mass
or volume, is an intensive property is discussed.
August, 2000
V-B. (Cont.)
The teachers then use density to identify an
unknown metal. Real world examples are
presented of how density is used to determine the
identity or purity of materials.
V-C. Predicting the Behavior of Matter
This activity provides an example of how certain
properties can be useful in predicting the behavior
of matter. The activity develops the idea that
density can be used to predict floating and sinking
behavior. Each group of teachers is supplied with
mineral oil and water (to which blue food coloring
has been added) and is asked to predict how the
liquids will layer if placed together. Before trying
this, groups share their predictions and the reasons
for them. After testing their predictions, groups
compare the densities of the liquids to the order in
which the liquids can be layered. The difference
between viscosity and density is discussed. Next,
participants test whether the idea just developed — the fact that liquids will layer based upon
differences in density — can be extended to
include a mixture of solids and liquids.
Participants are given a piece of opaque, white
plastic from a bleach bottle. Participants observe
what happens when the three materials are put in a
clear bottle. (The white plastic can be cut into the
shape of a boat before inserting to make a wave
bottle for a nice “Make and Take” activity.)
Afterwards, participants observe a silent
demonstration conducted by the workshop leader.
A candle is cut into two unequal pieces (one large
and one small), and the pieces are placed into two
different beakers, each containing an unidentified
clear liquid (one beaker contains water and the
other alcohol). The participants are asked to
account for their observations and to make a
prediction as to what will happen if the two candle
pieces are switched. After the demonstration is
complete, participants discuss their explanations
and predictions.
© OPPS - Louisiana State University
64
Operation Primary Physical Science
V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
V-C. (Cont.)
The overall activity culminates by having the
participants consider whether the floating and
sinking phenomena they have observed can be
explained in terms of the particle model of matter
developed earlier in the workshop.
V-D. Make Sense
Teachers are given the opportunity to reflect on
and make sense of what they have learned during
the inquiry. They begin this process by observing
and trying to explain a cylinder containing a golf
ball layered between two liquids (water and salt
water) They also add to and/or modify their list of
“Ideas about Solids, Liquids, and Gases” and
revisit their list of “Questions about Solids,
Liquids, and Gases.”
SCIENCE IDEAS
•
•
•
•
•
All matter has mass and volume.
The ratio of the mass:volume of a
substance is a constant and is known as
the density of the substance.
Density is useful in predicting the floating
and sinking behavior of solids, liquids,
and gases.
An object will float in a fluid that is more
dense and sink in a fluid that is less
dense.
Substances can be identified by their
density.
V-E. Apply
Teachers are given samples of the 6 types of
recyclable plastics and are asked to invent a
scheme, using varying concentrations of salt
water, to identify an unlabeled sample of one of
these. They are then given an unknown sample to
try to identify using the scheme they have
designed.
August, 2000
© OPPS - Louisiana State University
65
Operation Primary Physical Science
V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
MATERIALS:
V-A. Common Properties of Solids,
Liquids, and Gases
For each group:
• sheet of chart or poster paper
• marker
V-B. Exploring Mass and Volume
For each group:
• balance
• graduated cylinder(s)
• metric ruler
• overflow can (optional)
• unknown metal sample
• a different kind of matter to investigate**
Examples: water
different sizes of Styrofoam ®
blocks
paper clips
oil
blocks of wood
copper shot
**Groups will need a sufficient amount to
have five different-sized samples of the
matter. Keep the purpose of the activity in
mind when selecting matter samples.
Choose materials that for various reasons
are difficult to measure (such as a material
that floats in water) so that the participants
will have to search for ways to overcome
such difficulties in addition to seeking an
answer to the investigation question.
August, 2000
V-C. Predicting the Behavior of Matter
For each group:
•
beaker or cup of mineral oil
•
beaker or cup of blue water (water to
which food coloring is added)
•
empty beaker
•
piece of white plastic cut from bleach
bottle
•
clear and clean soda bottle, 16 oz.
•
scissors
For whole group
• large (600 ml - 1000 ml) beaker of water
• large (600 ml - 1000 ml) beaker of alcohol
• utility candle
• knife (for cutting candle into a small and
large piece)
• tongs
V-D. MakE Sense
For whole group:
• tall cylinder containing salt water, golf
ball, and distilled water
(a clear plastic tennis ball can works well
for the container)
V-E. Apply
For each group:
• samples of each plastic, #1-#6 (see
activity sheet for sources)
• beakers or other containers
• water
• tongs
• unknown plastic sample
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
A. Common Properties of Solids, Liquids, and Gases
Advance Preparation : Give each group a marker and a sheet of poster or chart paper on which to
draw their Venn diagram.
Hopefully, almost every group will have
put mass and volume as properties in the
center of the Venn diagram. Draw out
the idea that all matter — solids, liquids,
and gases — has in common the
properties of mass and volume. The
definition of matter as “anything that
has mass and takes up space” should be
discussed in this light.
Ask participants to think of everyday
situations in which mass or volume is
used to indicate the amount of matter
(such as at the grocery store). Get
participants to identify grocery products
that are sold by volume and products
that are sold by mass.
Ask participants to voluntarily describe
different ways of measuring the mass
and volume of solids, liquids, and gases.
Add to this discussion as needed. Have
measuring instruments and tools
available to demonstrate each procedure
as it is described.
V-A. Common Properties of Solids, Liquids, and Gases
1. Think back on all of the properties of
matter you have identified since the very
first activity in this workshop. Work with
your group to make a giant Venn diagram
that shows the properties of solids,
liquids, and gases. Try to include all of
the properties you have identified on the
diagram. Do some of the properties apply
to solids, liquids, and gases? When you
are finished, post your group’s diagram
for everyone to see.
2. Compare all of the Venn diagrams.
Did everyone agree on the properties to
include in the center of the diagram?
Solids
Liquids
Gases
End the activity by pointing out that,
while mass and volume are important
properties because they are characteristic of all matter and because they allow
us to express how much we have of
something, they are not very useful in
describing a particular kind of matter
because their values change with the
amount of matter present. This leads
into the next activity, which asks
participants to see if there is perhaps a
useful relationship between mass and
volume.
August, 2000
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
A. Common Properties of Solids, Liquids, and Gases (Cont.)
Here is an example of a VENN diagram produced by one group of SOLIDS, LIQUIDS, and GASES.
SOLIDS
definite shape
hardness
texture
tensile strength
elasticity
GASES
definite volume
noncompressibility
cohesion
mass
volume
no definable volume
compressibility
viscosity
surface
fluidity
no definite shape
diffusion
LIQUIDS
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
B. Exploring Mass and Volume
Introduce this activity with the following situation: “You have a certain amount of gold. A rich uncle
gives you some more gold so that you now have twice as much. Do you have twice the mass or twice the
volume? Of course, the answer is that both the mass and the volume will double. As one increases, the
other increases proportionally. This suggests that there is a definite relationship between the mass and
volume of a substance. Let’s explore this idea further in this activity.”
V-B. Exploring Mass and Volume
Give groups about 30 minutes to work on
this. Anticipate that some groups may
simply produce tabulated data, others
may look at ratios, and others may
produce some type of graph. Be
prepared to respond to each of these.
1. The mass and the volume of a
substance do not tell you much about the
nature of the substance itself, but perhaps
there is a useful relationship between
mass and volume. Record all of your
data in an organized fashion, and be
prepared to share your data and your
conclusions with the other groups.
Let groups take turns presenting their
data and conclusions.
Hold a round-up discussion. Help all
teachers to recognize that there is a
constant relationship between mass and
volume, and there are a couple of ways
that this relationship might be expressed.
Point out that scientists express this
relationship in terms of mass/volume,
and the term they use to refer to this is
“density.” (Teachers may have already
keyed in to this. If so, not as much
discussion about density is necessary.)
Try to help teachers develop a mental
model for density, such as envisioning a
dense forest — a lot of matter crowded
into a space.
For the next step of the activity, provide
each group with a relatively pure sample
of a metal (it is not necessary for all
groups to have the same metal) and a
table of densities of common metals.
August, 2000
3. Your group has been given a sample
of an unidentified metal. Find the density
of the metal, then compare it to a table of
known densities of various metals. Can
you guess what your metal probably is?
Metal
Density
Aluminum
2.7 g/cm3
Copper
8.1 g/cm3
Iron
8.3 g/cm3
Zinc
7.9 g/cm3
Lead
11.4 g/cm3
2. Present your data and conclusions to
the other groups, and listen carefully as
they share theirs with you. Did everyone
use the same approach in analyzing their
data? Did everyone reach the same
conclusion?
Check groups’ results. Ask participants to discuss the
reliability of their results, and to suggest ways of improving
reliability. You may want to use this as an opportunity to
talk about how scientists express the degree of error in their
measurements and calculated results. Give real-world
examples of how density is used to identify or determine the
purity of materials.
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Operation Primary Physical Science
V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
C. Predicting the Behavior of Matter
Introduce the activity by telling the participants that they are going to see if there is a way that they can
predict the floating and sinking behavior of matter.
Distribute, or make available at a
central location, containers (plastic cups
or beakers) of water and mineral oil.
Point out that a couple of drops of food
coloring have been added to the water to
turn it blue so that it can be visually
distinguished from the mineral oil. Also
distribute pieces cut from a white bleach
bottle.
Allow participants to discuss and
compare their ideas in their groups, and
then share them with the larger group.
Expect that some teachers will predict
that the liquids will layer based upon
differences in viscosity; with the most
viscous liquid, oil, on the bottom. Others
will know that they will layer based upon
density. Others will know that the oil
will be on top because of personal experiences or prior knowledge, even if
they can’t supply a scientific reason for
it.
If all groups are proceeding at about the
same pace, have them stop at this point
to compare results.
At an appropriate time in the activity,
and you will have to be the judge of
when that is, discuss the difference
between viscosity and density. Explain
that most people think that more viscous
liquids are also denser, but that is not
necessarily the case, as can be seen in
this activity.
August, 2000
V-C. Predicting the Behavior of Matter
1. Examine your mineral oil and water
samples. What do you think would
happen of you added them together? DO
NOT do it at this time! Do you think one
would float on top of the other? Which
one? Is there a way you can verify your
prediction without actually adding the two
liquids together?
4. What do you think will happen if all
three substances are added together in
the same container? Cut a small piece of
the white plastic into the shape of a boat.
Pour your mineral oil and your blue water
into a 16 oz. soda bottle. Drop in the little
boat. Shake, and observe what happens.
Were your predictions correct?
2. Make a prediction about how the
densities of the oil and water compare.
Do your predictions agree with those of
others in you group? Actually determine
the density of each of the liquids to verify
your predictions.
5. From your observations, what can you
infer about differences between the
particles of oil, water, and plastic? Work
with your group to come up with a
possible particle diagram for the bottle’s
contents that might account for your
observations. Can your group think of a
different particle diagram that would
account just as well for what happened?
3. Cut a couple of small pieces of white
plastic from the larger piece. Drop one in
the water and one in the mineral oil.
Record your observations. What does
this tell you about the differences
between water, mineral oil, and plastic?
Discuss your ideas with your group.
It is suggested that you provide the participants with chart
paper for this task. This way groups can take turns showing
the model they envisioned. This can lead to a rich debate as
groups critique each other’s ideas. Reserve judgment for
the follow-up discussion.
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
C. Predicting the Behavior of Matter (Cont.)
Activity Follow-up
A Particle Model to Explain Density
Use participant responses in the last step of the activity to lead into a discussion of how we
can explain differences in density using a particle model. Ask participants to think about
whether differences in densities of materials can be explained by
— differences in the closeness of the particles?
— differences in the mass of the particles?
— differences in the size of the particles?
— other factors?
— a combination of the above factors?
Use a concrete model to help participants reason through these questions.
Differences in closeness: Suppose two materials are made of particles that have exactly the
same mass and are exactly the same size. Could a difference in the spacing of the particles
result in one material being denser than another? Answer: Yes. Imagine golf balls packed
close together versus golf balls spread apart. Obviously, with the packed golf balls, there is a
greater mass in the same amount of space.
Golf Balls Closely Packed
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Golf Balls Spread Apart
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Operation Primary Physical Science
V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
C. Predicting the Behavior of Matter
Activity Follow-up (Cont.)
A Particle Model to Explain Density (Cont.)
Difference in the mass of the particles: Suppose two materials are made of particles that are
the same size and have the same amount of space between them. Could a difference in the
mass of the particles result in one material being denser than the other? Consider a box
packed with 144 ping pong balls and another, identical box packed with 144 golf balls.
Which is denser? The box of golf balls, because it has much greater mass in the same
amount of space.
Ping Pong Balls
Golf Balls
Differences in volume: Suppose two materials have particles of the same mass, but the
particles of one material are much larger than the particles of the other. Could this result in
one material being denser than the other? Imagine you have large rubber balls and small steel
balls that have the same mass. If they are each packed as closely together into identical
boxes, how will their densities compare? Obviously, because a lot more small balls can fit
into a box, the box of steel balls is densest because there is a lot more mass in the same
amount of space.
Rubber Balls
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Steel Balls
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
C. Predicting the Behavior of Matter
Activity Follow-up (Cont.)
Usefulness of density in predicting floating and sinking
Discuss how, by knowing the densities of the materials involved, we can predict whether one
material will float or sink in another. This serves as an example of how some properties are
very useful in predicting behavior. Ask participants to brainstorm other specific examples of
properties that can be used to predict behavior.
Making inferences about floating and sinking
Conduct the elicitation activity (the first activity) from the previous Nature of Matter module.
participants observe a silent demonstration conducted by the workshop leader. A candle is cut
into two unequal pieces (one large and one small) and the pieces are placed into two different
beakers, each containing an unidentified clear liquid (one beaker contains water and the other
alcohol). The participants are asked to account for their observations and to make a prediction
as to what will happen if the two candle pieces are switched. After the demonstration is
complete, participants discuss their observations and explanations.
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
D. Make Sense
You may substitute tap water, if distilled
water is not available.
V-D. Make Sense
Let groups share the changes they have
made to their lists. Try to clear up any
confusions that the participants seem to
have. Since this is the end of the content
portion of the workshop, you want to try
to avoid, if at all possible, ending the
workshop with the participants feeling
confused or uncertain about the ideas
that have been investigated. Hold a
whole group discussion and make final
changes and additions to the consensual
list in the front of the room. Make sure
that everyone understands and agrees
with the language used to express these
consensual ideas.
Do not share these as a large group at
this time. Participants will take a final
look at their lists of questions after the
next activity (which concludes the
content portion of the workshop).
August, 2000
1. Study the cylinder in the front of the
room. It contains salt water, distilled
water, and a golf ball.
3. Revisit your list of “Questions about
Solids, Liquids, and Gases.” Mark
through the questions that you can now
answer. Add any new questions that
have arisen.
a) Which liquid is on top, the salt water or
the distilled (pure) water? How do you
know? What do other members of your
group think?
b) Draw a particle picture of the contents
of the cylinder. Compare your drawing
with the drawings of others in your group.
2. Get out, for a final time, your group’s
list of “Ideas about Solids, Liquids, and
Gases.” Have any of your ideas
changed? Do you need to add any new
ideas? Make these changes and
additions to your list.
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V. INQUIRE Are Some Properties More Important or More Useful
to Know than Others
E. Apply
Pass plastic containers, and other
products made of the different kinds of
plastic, around so the participants can
find and examine the recycling code. If
possible, have more than one example of
each type of plastic. Make the point that
because the the same kind of plastic can
vary in color, transparency etc., if a
product did not have a recycling code it
would be almost impossible to identify
the plastic by visual inspection.
Have pieces of “unknown” plastic ready
to distribute to groups as they finish
preparing their solutions.
V-E. Apply
1. There are six types of plastic that can be recycled, but these different types cannot
be melted together to create new plastic products. Each kind must be recycled
separately. For this reason, most plastic containers and other disposable plastic
products are marked with a number from 1-6 which appears inside the recycling
symbol and indicates the plastic type.
Number
Plastic (chemical name)
Example Product
1
Polyethylene terphthalate (PETE)
soda bottles
2
High density polyethylene (HDPE)
milk jugs
3
Polyethylene
Ziploc bag
4
Low density polyethylene (LDPE)
catsup bottle
5
Polypropylene (PP)
sour cream container
6
Polystyrene (PS)
clear deli containers
2. Each of these plastics have a different density. This means that they differ in their
floating and sinking behavior. Using your knowledge of density, floating, and sinking,
work with other members of your group to prepare a set of salt water solutions of
different concentrations that you could use to identify unmarked pieces of plastic. Your
workshop leader will give you a sample of each of the six plastics that you can use to
prepare and test your salt water solutions.
3. Your workshop leader will now give you an unknown plastic to identify.
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VI. REFLECT Can We Use What We’ve Learned?
You may want each group to use its own
list of ideas, or you may prefer all
groups to use the consensual list. (There
are pros and cons for each way of doing
it.)
VI. Reflect
Before embarking on this task, you may
want to discuss with participants the
importance of evidence in science. Point
out, through the use of examples, that
“evidence” is what separates science
from pseudoscience.
1. In science, ’how’ you know is every bit
as important as ’what’ you know. Look at
the final list of “Ideas about Solids,
Liquids, and Gases.” This is a list of
‘what’ you know. Now, working with your
group, describe ‘how’ you know. For
each idea on the list, write one or more
examples of evidence that supports the
idea. The evidence may come from
observations you have made during this
workshop, or from other experiences you
have had.
2. Examine the list of ideas in the sheet
that your workshop leader has distributed.
How do these compare with the ideas you
developed during the workshop?
Groups may need an example or two to
help them get started with this task.
Idea:
Gases are compressible.
Evidence: You could squeeze the gas in
the syringe into a smaller
amount of space.
Distribute “Some Key Ideas about
Solids, Liquids, and Gases.” Explain to
the participants that these are the ideas
you had hoped they would develop an
understanding of during the workshop.
Tell them that they might want to keep
this list, which also includes
explanations and examples, for future
reference.
Try to address any questions that arise
from this comparison. It is expected that
there will be differences in the phrasing
and terminology used on the two lists.
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Appendix
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The Particle Model of Matter
Solids
Particles are:
•
•
•
•
closely packed
in regular arrays
vibrating about a fixed point
strongly bonded
Liquids
Particles are:
•
•
•
•
closely packed
arranged irregularly
moving past one another
weakly bonded
Gases
Particles are:
•
•
•
•
August, 2000
well spaced out
arranged at random
moving very rapidly
not bonded
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How do liquids behave in a range of containers?
Before
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After
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APPENDIX
Varying Properties of Solids
Hardness
Definition: Hardness is the degree to which a substance resists abrasion, scratching, or
penetration of its surface.
Example: Ceramic tile floors are not easily scratched or dented and last for many, many years.
Linoleum flooring is more easily scratched and dented and after several years may show bare
spots where the linoleum has worn away. On the other hand, linole um is more comfortable to
stand and walk on and less likely to cause tired feet or backaches.
Measuring/Rating: The simplest way to compare the hardness of two different materials is to
try scratching each with the other. A material can scratch another material that is softer than
itself but cannot scratch one that is harder. Geologists have developed a scale called the Moh’s
scale to rate the hardness of different rocks and minerals.
Tensile Strength
Definition: Tensile strength is the size of the pulling or stretching force that a substance can
withstand without tearing apart.
Example: Fishing line must have enough tensile strength to lift the fish out of the water without
breaking. Deep sea fishermen will use line with a greater tensile strength than someone fishing
with a cane pole in a small pond.
Measuring/Rating: Suspend lengths of different materials having the same cross-sectional
area, and add weights to each until it breaks or tears apart. The actual tensile strength of a
material is the force per cross-sectional area (lbs./in2 or N/cm2) that it can withstand. Materials
can simply be rank ordered, from greatest tensile strength to least tensile strength, by the
amount of force required to break or tear them. Another way to compare the tensile strength of
material is to stretch each material across an unbreakable cup or bowl and secure with a large
rubber band (or stretch across and an embroidery hoop) and then drop an object such as a
marble or steel ball onto the material from increasing heights until the material tears. The
greater the height of drop required to break the object, the greater the tensile strength of the
material (if all materials are of equal thickness).
Elasticity
Definition: Elasticity is how well a material returns to its original size and shape after a
deforming force has been removed.
Example: Good panty hose are highly elastic. This means they return to their original size and
shape after being stretched. Bubble gum, on the other hand, is highly inelastic; although it can
be easily stretched, it does not return to its original size and shape but remains deformed.
Measuring/Comparing: Materials of equal cross sectional area (such as equalized strips of
material of equal thickness) can be compared by measuring the original length of the material,
stretching it a certain amount, then measuring the length after stretching.
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APPENDIX
Varying Properties of Solids (cont.)
Absorbency
Definition: Absorbency is how well a material absorbs or soaks up a liquid. It is dependent on
the adherence between the liquid and the solid material.
Example: A good paper towel can absorb a large amount of water.
Measuring/Comparing: The absorbency of a material can be measured in terms of the amount
of liquid (either mass or volume) that it soaks up and hold. The absorbency of materials can
also be compared by placing an equal number of drops of liquid (water) on each and comparing
the size of the wet spots. Materials vary both in the amount of liquid they can absorb and in
how quickly they absorb a liquid. (Bounty® is the “quicker picker upper”)
Electrical Conductivity
Definition: Electrical conductivity refers to how well a material conducts an electric current.
Example: Copper is used in household wiring because it is a good conductor of electricity.
Meas uring/Comparing: The conductivity of materials can be by the brightness of a light bulb
in a simple battery/bulb circuit into which each is placed.
Heat Conductivity
Definition: Heat conductivity is how well a material conducts heat — how quickly heat can be
transferred through the material.
Example: Pots and pans are made of metal so that the greatest amount of heat from the stove
burner will be uniformly and quickly conducted to the food they contain. Pot and pan handles
are usually made of very poor heat conductors (insulators), so they will not conduct heat to your
hand.
Measuring/Comparing: Compare the heat conductivity of materials by measuring the
amount of time required for heat from a source to travel through a certain length of the
material to a detector such as a person’s hand or a piece of paraffin that will melt when the
heat reaches it. Materials should have the same cross-sectional area. For example, use
equal-sized strips having the same thickness, or use equal- length rods having the same
diameter
Permeability
Definition: The permeability of a solid is how well a liquid can flow through it.
Example: Soils must be permeable so that water can flow through them to the roots of
plants; however, if soils are too permeable, the water will flow through them too quickly to
be captured by the roots.
Measuring/Comparing: Place equal amounts of each material, in turn, in a cup that has a
small hole in the bottom. Pour a measured amount of water into the cup and record both the
amount of water that passes through into a collection bowl and the time required.
Permeability can be expressed in terms of the amount of water per unit of time (2 ml/sec).
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APPENDIX
Varying Properties of Liquids
Cohesion - the degree to which particles of a substance are attracted to one another; the “stick
togetherness” of a liquid.
Adhesion - the degree to which particles of one substance are attracted to particles of another
substance; how well a liquid adheres or sticks to another specified substance.
Viscosity - The characteristic of a liquid that causes it to resist flowing; the “thickness” of a
liquid.
Evaporation Rate - how quickly a liquid evaporates when exposed to the air at a given
temperature.
Boiling Point - the temperature at which a liquid is converted to a gas by boiling at normal
atmospheric pressure.
Freezing Po int - The temperature at which a liquid freezes or becomes solid.
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