10/4/2016
Nature of Science
Scientific Method Experimental Design
Agenda:
 Do-Now (15 mins)
 Experimental Design Vocab
(10 mins)
 Practice ID Components of
Experimental Design ( 20
mins)
Goals:

I can list the types of investigations typically carried out by
scientist

I can identify the independent, dependent and controlled
variables in an experiment
I can explain the importance of controls in scientific
investigations

Essential Question
How are scientific investigations designed
and conducted?
Homework:

Finish ID Variable Practice
Sheet
Do-Now:
Complete Station Work
WEEK-AT-A-GLANCE
Monday
Tuesday
Monday
Tuesday
Scientific Method
Introduction
Scientific Method
Experimental
Design
Wednesday
Thursday
Wednesday
Friday
Thursday
Scientific Method
Data Analysis
Scientific Method
Graphing
Friday
Scientific Method
Writing
Conclusions
Types of Scientific
Investigations
Different research
questions require different
types of investigations.
 Descriptive
Investigations
 Comparative
Investigations
 Experimental
Investigations
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Descriptive Investigation

 Has
a research
question,
procedures, and
conclusion


Descriptive Investigation: Involve
describing and/or quantifying
parts of a natural system.
Used when little is
known about the
topic No hypothesis or
prediction
Key words: Observe,
describe, list, identify
Example – observing cells under a
microscope and diagramming what is
seen.
Comparative Investigation
 Has
a research question,
possible hypothesis,
procedures, and
conclusion.



Comparative Investigation:
Involve collecting data on
different populations/organisms,
under different conditions (ex.
Times of year, locations), to
make a comparison.
Can have independent/manipulated
and dependent/response variables
No control / control group
Key words: Compare/contrast,
similarity/difference, categorize
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Experimental Investigation
 All
known variables
have been identified



Has a research question,
hypothesis, procedures,
control, and conclusion
Has independent and
dependent variables

Experimental Investigation:
Involve a process in which a
“fair test” is designed in which
variables are actively
manipulated, controlled, and
measured in an effort to
gather evidence to support or
refute a causal relationship.
All factors must be held
constant except the
manipulated (independent
variable)
Example- Testing the height of a ramp to
determine how far a marble will roll. Or
the effect of fertilizer on the height of a
plant.
*Most scientific investigations you do in science
class will be experimental investigations
Latin Root
Vari – to change
Experimental Investigations Have
Variables
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Essential Question?
How are experimental investigations
designed and conducted?
A
CONTROLLED EXPERIMENTAL INVESTIGATION is a
test of the effect of a single variable by changing
it while keeping all other variables the same.
Example;
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10/4/2016
Quick Write
Why was it important for Mark and Molly to
keep everything the same between the two
plants but the amount of water used?
Essential Vocabulary
Controlled Experiment Vocabulary
Independent Variable (aka –
manipulated variable)
The condition the experimenter
manipulates (changes ON
PURPOSE)
Dependent Variable (aka –
responding variable)
The result or outcome that the
experimenter wants to know (it
may on may not change)
Controlled variable (aka
constants)
The conditions that are the same
in all trials
Trial
one of a number of repetitions of
an experiment
Control Group
The group used as a basis of
comparison (usually found at
either extreme of the data
gathered)
Experimental Group
The group treated differently from
the control group (usually has the
independent variable present)
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Let’s Practice
Read the following description of an experiment
and identify the elements
Sam wished to investigate how fertilizer run-off
affects the growth of algae in freshwater lakes
and streams. He set his experiment up this way.
He placed 900 Ml of water into (5) 1,000 Ml glass
beakers.
What is/are the…
To each beaker he added 5 Ml of water from an
aquarium which contained a large concentration
of algae.
The beakers were placed under a grow light
which was timed to provide 12 hours of light each
day.
Independent Variable?
Liquid fertilizer was added to the beakers in the
following amounts;
Dependent Variable?
Beaker 1- no fertilizer
Beaker 2 - 2 ml of fertilizer
Beaker 3 - 4 ml of fertilizer
Beaker 4 - 6 ml of fertilizer
Beaker 5 - 8 ml of fertilizer
Each week a random sample from each of the
beakers was examined under a microscope to
get a count of the number of algae cells present
Experimental Group?
Control Group?
Controlled Variables?
Practice #2
Read the following description of an
experiment and identify the elements
A study was created to test the effects
of jazz on people’s sleep patterns.
The hypothesis of the experiment was
that if people listened to jazz music as
they fall asleep, they will sleep for
longer periods of time because the
music would be soothing.
For the experiment, 2 groups of people
were created.

One group was placed in a quiet
room where they went to sleep and
they were timed on how long they
slept.

The other group was placed in a
room where jazz music played softly
as they began to sleep and played
throughout the night.
As each group awoke, their sleep times
were monitored.
Identify the …..
Independent Variable?
Dependent Variable?
Experimental Group?
Control Group?
List variables that should remain
constant in this experiment?
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Practice #3
Read the following description of an
experiment and identify the elements
Suzie Q wants to know the effect of
different colors of light on the growth of
plants.
She believes that plants can survive
best in white light.
She buys 5 ferns of the same species,
which are all approximately the same
age and height.
She places one each;
- in white light,
- in blue light
- in green light
- in red light
- in the closet.
All of the ferns are planted in MiracleGrow and given 20 mL of water once a
day for 2 weeks.
After the two weeks, Suzie observes the
plants and makes measurements.
Identify the….
Independent Variable?
Dependent Variable?
Experimental Group?
Control Group?
Controlled Variables?
Write a hypothesis for this
experiment.
What types of measurements can
Suzie make on the plants to
determine how they did in different
types of light
White Board Practice
Read the following and identify the
elements of the experiment
Henry wanted to know if the amount of salt in
water would affect how quickly the salt would
dissolve. He did some research about the
chemical components of salt and water. After
doing his research, Henry suggested a solution to
the problem. He believed the more salt that was
added to the water the faster the salt would
dissolve. He set up the following experiment to see
if he was correct.
Using large glass beaker, Henry placed the
following amount of salt in 400ml of water.
Beaker A - 6 grams
Beaker B - 12 grams
Beaker C - 18 grams
Beaker D - 24 grams
Beaker E - 30 grams
Beaker F - 1 gram
Henry used the same stirring pace and stirred the
water until no more salt crystals could be seen in
the beakers. Using his stopwatch, he timed how
long it took for the salt in each beaker to dissolve.
Using Henry's experiment,
answer the following
questions
1. What was the problem Henry was
trying to solve?
2. What was Henry's hypothesis?
3. What is the Independent Variable?
4. What is the Dependent Variable?
5. Which beaker represents Henry's
control group? Why?
6. List 4 controlled variables in this
experiment.
He repeated the entire procedure two more times.
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10/4/2016
Group Practice
SpongeBob loves to garden
and wants to grow lots of pink
flowers for his pal Sandy.
He bought a special Flower
Power fertilizer to see if it will
help plants produce more
flowers.
He plants two plants of the
same size in separate
containers with the same
amount of potting soil.
He places one plant in a sunny
window and waters it every day
with fertilized water.

What did SpongeBob
do wrong in this
experiment? Explain.

What should
SpongeBob do to test
the effectiveness of
Flower Power fertilizer?
Write an experiment.
He places the other plant on a
shelf in a closet and waters it
with plain water every other
day.
Practice Test Questions
Here are some examples of a question you might see on a quiz or test.
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Questions
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c.
The weight of the load
d. The type of robot
c. amount of water
d. the window
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Exit Slip

Kayla has always wondered why recipes usually
call for salt to be added to water when it’s
going to be boiled. She thinks it could be
because salt water reaches its boiling point
before tap water. She pours one cup of water
each into two identical pots. She adds a
tablespoon of salt to one pot and adds nothing
to the second pot. Then, she puts both pots on
the stove and turns it on. She monitors the
temperature of the water to see which pot
reaches 212ºF first.
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