A Standards-based Curriculum for Clay Science
Audrey C. Rule
Department of Curriculum and Instruction, 250-G Wilber Hall, State University of
New York at Oswego, Oswego, NY 13126, [email protected]
Stephen Guggenheim
Department of Earth and Environmental Sciences, University of Illinois at
Chicago, 845 W. Taylor St., Chicago, IL 60607, [email protected]
ABSTRACT
A prekindergarten to 12th grade curriculum for clay
science is presented based on the Benchmarks for science
literacy and the National science education standards. These
clay concepts support learning in chemistry, physical
science, and Earth science and are divided into concepts
and activities for early childhood, elementary, middle
school, and high school students. Two studies
addressing facets of the curriculum show the utility of
the proposed clay concepts and suggested lessons. More
work is needed to define specific ideas students may
have about clay in the rock cycle, clay's role in everyday
products, what clay scientists do, and to test the efficacy
of the entire curriculum.
INTRODUCTION
In the 1990's research focusing on human learning
showed that learning and retention in science increased
if students were actively involved in their learning and
engaged in inquiry. Because our society is increasingly
scientifically and technologically-oriented, there is a
need for all students, not just those preparing to become
scientists, to learn science as noted in Science for all
Americans (Rutherford, 1990). The science standards
movement in the United States began in 1985 through
Project 2061 of the American Association for the
Advancement of Science. This project analyzed the status
of United States education relative to other developed
countries and meetings were organized with scientists
and science educators to determine how best to improve
American science education. The Benchmarks for science
literacy (American Association for the Advancement of
Science, 1993) identified essential science content at four
grade level ranges (K-2, 3-5, 6-8, and 9-12). Important
content included the role of science inquiry and a basic
understanding of the characteristics of science. The
National Research Council, a branch of the National
Academy of Sciences, initiated a parallel standards
project in the early 1990's that was funded by the
National Science Foundation, called the National science
education standards (NSES) (1996). These standards
divided students into three grade levels, K-4, 5-8, and
9-12. The NSES contained standards for teaching science,
for professional development for science teachers, for
science assessment, and for local and system science
education programs. Both sets of standards are
recognized as important with similar sets of policies
(Bybee, 2006); they are in an estimated 90% agreement on
content in the life, Earth and physical sciences
(Rutherford, 1996). In this article, we consider both.
Development of Standards-based Curricula in
Science Disciplines - Standards-based curricula have
been developed in many science disciplines. For
example, the American Chemical Society (1997, 2002)
produced a reader and resource manual for high school
chemistry teachers that explained how chemistry related
to the national standards, and it showcased inquiry
lessons based on these standards. In chapter one,
Heikkinen addressed the ultimate goal (the "ends") of
education reform to improve science learning. He
suggested a greater direct emphasis on the students
rather than the "means" of improved instruction, such as
better textbooks, more-inquiry-oriented activities, and
more authentic assessments. Heikkinen used an analogy
of nutritional standards and meals to explain the use of
science standards to produce a variety of appropriate
curricula. Just as a wide range of diets and cuisines can
support identical nutritional standards, a diversity of
science lessons can satisfy the science education
standards.
The National Science Foundation has funded the
development of many standards-based curriculum
programs. For example, in biology, three curriculum
projects (Leonard, 2004) were developed with the NSES
that incorporated current cognate research and recent
biology content, and that focused on in-depth learning in
a few selected areas and emphasized inquiry. These three
programs are: BSCS: A Human Approach (BSCS, 1997 and
2003); Insights in Biology (Education Development
Corporation, 1998); and Biology: A Community Context
(Leonard and Penick, 1998 and 2003).
Adams and Slater (2000) presented an analysis of
astronomy concepts in the NSES. They not only
identified astronomy-related concepts and discussed
their implementation at different grade levels, but they
also reviewed the literature on science misconception
research related to these ideas.
Heikkinen (1997, 2002) noted that although the
words "chemistry," "biology," "physics," "geology," and
"astronomy" do not appear in the table of contents or
index in either the Benchmarks for Science Literacy or the
NSES, these concepts are embedded in a more integrated
organization of the facts, ideas, and skills of science
presented by these two works. Similarly, although "clay
science" is not a component part, clay science concepts
are integral to these two standards documents. In this
article, we analyze these documents to identify clay
science concepts at different grade levels to answer these
three questions, "What clay concepts are important and
supported by other science learning at different grade
level ranges?" "What activities might be used to teach
them?" and "What do we know about student difficulties
in learning these concepts?"
Why Teach K-12 Students about Clays? - Clay science
is not one of the basic sciences, but an introduction to the
study of clays can readily illustrate aspects of physical
science, life science, Earth and space science, and
mathematics. Furthermore, clay science, as a
sub-discipline of Earth science, can be used to exemplify
and integrate ideas from other sciences, and to introduce
other more specialized disciplines, such as agricultural
science, archeology, and engineering. Clay science plays
a role in society-related questions such as, "How can we
properly dispose of chemical or nuclear waste in landfills
while protecting groundwater?" or "What is involved in
sustaining a food supply for the growing world
Rule and Guggenheim - A Standards-based Curriculum for Clay Science
257
Standard from Benchmarks for Science
Literacy
Chunks of rocks come in many sizes and
shapes, from boulders to grains of sand and
even smaller. [PreK-2; 4. The Physical
Setting, C. Processes that shape the Earth]
Change is something that happens to many
things. [PreK-2; 4. The Physical Setting, C.
Processes that shape the Earth]
Things can be done to materials to change
some of their properties, but not all
materials respond the same way to what is
done to them. [PreK-2; 4. The Physical
Setting, D. The Structure of Matter]
Objects can be described in terms of the
materials they are made of (clay, cloth,
paper, etc.) and their physical properties
(color, size, shape, weight, texture,
flexibility, etc.). [PreK-2; 4. The Physical
Setting, D. The Structure of Matter]
Some kinds of materials are better than
others for making any particular thing.
Materials that are better in some ways (such
as stronger or cheaper) may be worse in
other ways (heavier or harder to cut).
[PreK-2; 8. The Designed World B. Materials
and Manufacturing]
Several steps are usually involved in
making things. [PreK-2; 8. The Designed
World B. Materials and Manufacturing]
Tools are used to help make things, and
some things cannot be made at all without
tools. Each kind of tool has a special
purpose. [PreK-2; 8. The Designed World B.
Materials and Manufacturing]
Standard from National Science
Education Standards
Objects have many observable properties,
including size, weight, shape, color,
temperature, and the ability to react with
other substances. Those properties can be
measured using tools, such as rulers,
balances, and thermometers. [K-4; Physical
Science Content Standard B, Properties of
objects and materials]
Materials can exist in different states--solid,
liquid, and gas. Some common materials,
such as water, can be changed from one
state to another by heating or cooling. [K-4;
Physical Science Content Standard B,
Properties of objects and materials]
Earth materials are solid rocks and soils,
water, and the gases of the atmosphere. The
varied materials have different physical and
chemical properties, which make them
useful in different ways, for example, as
building materials, as sources of fuel, or for
growing the plants we use as food. Earth
materials provide many of the resources
that humans use. [K-4; Earth and Space
Science Content Standard D, Properties of
Earth Materials]
People have always had problems and
invented tools and techniques (ways of
doing something) to solve problems. Trying
to determine the effects of solutions helps
people avoid some new problems.[K-4;
Science and Technology Content Standard
E, Understanding about Science and
Technology]
Clay Concept and Suggested Activity
Mud is usually wet clay with sand or other
small particles intermixed. Clay is made of
particles smaller than sand - so small we
cannot see their outlines. Most soil contains
much clay along with organic materials.
Activity: Identify local places when clay
can be seen (field, ditch, road cut,
schoolyard). Examine mud samples from
different places using a magnifying glass.
Describe their characteristics.
Clay changes when it is wet. Wet clay can
be pressed, rolled, and molded into intricate
shapes. When clay dries, it is brittle.
Activity: Experiment with rolling,
pressing, molding, impressing damp clay.
Emphasize descriptive vocabulary.
Activity: Compare wet/damp sand to
wet/damp clay. Compare wet clay to dry
clay. Emphasize descriptive vocabulary.
Many household items are made of or
contain clay. Flowerpots, teacups and
dishes, and toilets started out as clay.
Toothpaste contains clay. Cat litter is dried
clay.
Activity: Assemble a classroom collection
of objects that are made with clay.
Organize the collection.
Clays can be used to absorb liquids, such as
urine in cat litter. Sand would not work as
well.
Ceramics are used for dishes because they
are hard, non-porous, and good insulators.
Activity: Pour water on cat litter. Make
observations.
The steps in making pottery are: mine the
clay, form the pot and let it dry, fire the pot,
glaze the pot, fire the pot, etc.
Activity: Make a simple pinch pot. List the
steps in detail.
Potters may use a wheel to make round,
symmetrical clay pots.
Activity: Use a wheel or other tools to
make a clay pot.
Table 1. Suggested clay science activities for early childhood students linked to standards
population?" In addition, clay (or its synthetic
equivalent) is familiar to most children from very early
ages. This familiarity is commonly related to play and
art, from the use of simple molds to make clay forms to
the intricate work of using a potter's wheel to form vases.
Familiarity, however, is much broader than first realized
by most; clays are a commodity of great importance in
objects we use everyday, both inside our homes (e.g.,
ceramics, pharmaceuticals, cosmetics, plastics, paper),
and outside (e.g., bricks, cement, tires, paints), although
the listed examples are not mutually exclusive.
A clay-science curriculum can begin by utilizing a
child's interest in clay as an art form. Alternatively, a
student's attention can be drawn to clay as a moldable
material when wet but also to products that may,
perhaps surprisingly so, involve clay that is clearly not
related to its moldable qualities directly. For the former,
events are more likely to be remembered if new learning
is based on previous experience (i.e., clay objects as an art
form). For the latter, students may not at first realize how
clay that is moldable can be used in the making of paper,
which clearly does not have this property. In this case,
learning is enhanced by a perceived contradiction or new
and unknown circumstances. Curiosity may be aroused
at many levels, as is observed in the early childhood,
258
elementary, middle school and high school activities that
follow.
CLAY SCIENCE OBJECTIVES
This article provides a content analysis of the Benchmarks
for science literacy and the National science education
standards to determine where clay science supports a
standards-based curriculum for preK-12 students. In the
accompanying tables, pertinent standards are given in
the first two columns with clay concepts and suggested
activities in the final column. Ideas presented in the
tables are expanded in the text.
Clay Science for Early Childhood Students - Early
childhood is a time of concrete exploration. Young
children are curious about the world and build personal
theories to explain what they see happening. Children's
ideas are built on their limited experiences and may be
reasonable or unreasonable, and possibly incomplete or
inconsistent with scientific thought. Science experiences
should involve young students in inquiry, during which
they explore events or materials, ask questions,
investigate to gather further information, record and
represent their work, and reflect on the meaning of their
Journal of Geoscience Education, v. 55, n. 4, September, 2007, p. 257-266
Standard from Benchmarks for Science
Literacy
Materials may be composed of parts that are
too small to be seen without magnification.
[3-5; 4. The Physical Setting, D. The
Structure of Matter]
Standard from National Science
Education Standards
Tools help scientists make better
observations, measurements, and
equipment for investigations. They help
scientists see, measure, and do things that
they could not otherwise see, measure, and
do. [K-4; Science and Technology Content
Standard E, Understanding about Science
and Technology]
Clay Concept and Suggested Activity
Clay particles are too small to be seen
without a microscope.
Activity: Examine scanning electron
microscope (SEM) photographs of clays
and other substances (salt crystals,
computer chips) or life forms (dust mites,
insects).
Clay can be baked (fired) at a very high
temperature in a special oven (kiln) and
permanently changed into a harder material
(ceramic). Dishes, flowerpots, toilets, tiles,
sewer pipes are often ceramic.
Activity: Compare natural clay or
greenware with a variety of ceramic items.
Describe physical properties when wet,
dry, and fired.
Ceramic materials are often good insulators
and used for dishes, floor and kitchen
counter tiles, and electrical fixtures.
Activity: Compare heat conduction of a
ceramic mug, a plastic mug, and a paper
cup filled with a hot liquid (tea or hot
chocolate).
Heating and cooling cause changes in the
properties of materials. [3-5; 4. The Physical
Setting, D. The Structure of Matter]
Naturally occurring materials such as wood,
clay, cotton, and animal skins may be
processed or combined with other materials
to change their properties. [3-5; 8. The
Designed World B. Materials and
Manufacturing]
Substances react chemically in characteristic
ways with other substances to form new
substances (compounds) with different
characteristic properties. [5-8; Physical
Science, Content Standard B, Properties and
Changes of Properties in Matter]
Some materials conduct heat much better
than others. Poor conductors can reduce
heat loss. [3-5; 4. The Physical Setting, E.
Energy Transformations]
Heat moves in predictable ways, flowing
from warmer objects to cooler ones, until
both reach the same temperature. [5-8;
Physical Science Content Standard B,
Transfer of Energy]
When a new material is made by combining
two or more materials, it has properties that
are different from the original materials. For
that reason, a lot of different materials can
be made from a small number of basic kinds
of materials. [3-5; 4. The Physical Setting, D.
The Structure of Matter]
A mixture of substances often can be
separated into the original substances using
one or more of the characteristic properties.
[5-8; Physical Science, Content Standard B,
Properties and Changes of Properties in
Matter].
People in less technologically advanced
societies added grass, ground shell, or sand
to clay (temper), as they made pottery, to
keep it from cracking and shrinking when it
dried.
Activity: Experiment with making statues
from plain clay and clay with laundry lint
worked in. Describe how the fibers
reinforce the material.
Soil is made partly from weathered rock,
partly from plant remains-and also contains
many living organisms. [3-5; 4. The Physical
Setting, C. Processes that shape the Earth]
Soils have properties of color and texture,
capacity to retain water, and ability to
support the growth of many kinds of plants,
including those in our food supply. [K-4;
Earth and Space Science Content Standard
D, Properties of Earth Materials]
Soil is composed of clays, rock particles, and
organic materials, including organisms. Soil
must be able to support life and is located
where it has formed versus regolith.
Activity: Investigate soil samples from
different local places. Identify some of the
life forms present. Create a poster display
of findings.
The surface of the Earth changes. Some
changes are [related] to slow processes, such
as erosion and weathering, and some
changes are due to rapid processes, such as
landslides, volcanic eruptions, and
earthquakes. [K-4; Earth and Space Science
Content Standard D, Changes in the Earth
and Sky]
Landforms are the result of a combination
of constructive and destructive forces.
Constructive forces include crustal
deformation, volcanic eruption, and
deposition of sediment, [whereas]
destructive forces include weathering and
erosion. [5-8; Earth and Space Science
Content Standard D, Structure of the Earth
System.]
Clay, because of its small particle size and
platy habit, is usually unaffected by wind or
water movement. However, once sediment
becomes suspended in water it becomes
more effective in erosion. Clay tends to stay
in suspension. It takes a long time for clays
to settle out of water or air. Clay forms
layers below the quiet waters of lakes and
deep oceans. Floodwaters leave behind clay
deposits.
Activity: Shake a jar with sand, silt, clay
and water. Watch the particles settle. How
long before the clays settle? Smear a lump
of clay into a pan and an equal amount of
sand. Run a fan and then pour water over
both and make observations.
Clay is not ground-up rock. Clay forms
when rocks weather and change into new
minerals of small particle size, some of
which are clays.
Activity: View photomicrographs of
hexagonal kaolinite crystals.
Many different people in different cultures
have made and continue to make
contributions to science and technology.
[5-8; Science and Technology Content
Standard E, Understandings about Science
and Technology.]
Technology influences society through its
products and processes. Technology
influences the quality of life and the ways
people act and interact. Technological
changes are often accompanied by social,
political, and economic changes that can be
beneficial or detrimental to individuals and
to society. [5-8; Science and Technology
Content Standard E, Science and
Technology in Society.]
In some parts of the world, people make
utilitarian pottery by hand. Also, artists
often hand make ceramic works. However,
in technologically developed countries,
pottery and other products utilizing clays
(paper, paint, toothpaste, pharmaceutical
tablets) are produced using automated
machines.
Activity: Investigate the history of
ceramics. How did the use of pottery
impact society? Compare ancient and
modern methods of making pottery.
Waves, wind, water, and ice shape and
reshape the Earth's land surface by eroding
rock and soil in some areas and depositing
them in other areas, sometimes in seasonal
layers. [3-5; 4. The Physical Setting, C.
Processes that shape the Earth]
Rock is composed of different combinations
of minerals. Smaller rocks come from the
breakage and weathering of bedrock and
larger rocks. [3-5; 4. The Physical Setting, C.
Processes that shape the Earth]
Through mass production, the time
required to make a product and its cost can
be greatly reduced. Although many things
are still made by hand in some parts of the
world, almost everything in the most
technologically developed countries is now
produced using automatic machines. Even
automatic machines require human
supervision. [3-5; 8. The Designed World B.
Materials and Manufacturing]
Table 2. Suggested clay science activities for elementary students linked to standards.
Rule and Guggenheim - A Standards-based Curriculum for Clay Science
259
Standard from Benchmarks for Science
Literacy
Sediments of sand and smaller particles
(sometimes containing the remains of
organisms) are gradually buried and are
cemented together by dissolved minerals to
form solid rock again. [6-8; 4. The Physical
Setting, C. Processes that shape the Earth]
Sedimentary rock buried [sufficiently] deep
may be reformed by pressure and heat,
perhaps melting and recrystallizing into
different kinds of rock. Rock bears evidence
of the minerals, temperatures, and forces
that created it. [6-8; 4. The Physical Setting,
C. Processes that shape the Earth]
Atoms [bond] together in well-defined
molecules or may be packed together in
large arrays. Different arrangements of
atoms into groups [comprise] all substances.
[6-8; 4. The Physical Setting, D. The
Structure of Matter]
The configuration of atoms in a molecule
determines the molecule's properties. [6-8; 4.
The Physical Setting, D. The Structure of
Matter]
The choice of materials for a job depends on
their properties and on how they interact
with other materials. [6-8; 8. The Designed
World B. Materials and Manufacturing]
Standard from National Science
Education Standards
Some changes in the solid Earth can be
described as the "rock cycle." Old rocks at
the Earth's surface weather, forming
sediments that are buried, then compacted,
heated, and often recrystallized into new
rock. Eventually, those new rocks may be
brought to the surface by the forces that
drive plate motions, and the rock cycle
continues. [5-8, Earth and Space Science
Content Standard D, Structure of the Earth
System.]
Clay Concept and Suggested Activity
Clays can become buried by overlying
deposits and compacted. Highly compacted
clays form mudstone, siltstones, and shale.
Activity: Examine these rocks. Identify
local areas where these may be seen.
Mudstones, siltstones, and shale may be
transformed into foliated metamorphic
rocks like schist or slate.
Activity: Examine mudstone, claystone,
siltstone, shale and compare to schist and
slate.
Clay minerals have a layered atomic
structure that affects their properties.
Activity: View drawings and models of
clay structures. View photomicrographs of
flat clay crystals.
The physical properties of compounds
reflect the nature of the interactions among
its molecules. These interactions are
determined by the structure of the molecule,
including the constituent atoms and the
distances and angles between them. [9-12;
Physical Science Content Standard B,
Structure and Properties of Matter]
The layer structure of clay minerals gives
them certain properties that are useful to
humans. The platy shape allows clays to
coat surfaces (clay makes paper smooth and
glossy, clay helps paints form a thick
coating, clay mixes well with plastics as
filler).
All clay is not alike. Clays are made of a
variety of different minerals called clay
minerals. Some clays have properties that
other clays do not have. Some clays swell
and absorb liquids. These clays are useful in
deodorant, lipstick and cat litter, or forming
gel in toothpaste.
Activity: Match products to clays with
specific properties as in these activities by
Rule (1997a, 1997b, 2007a, 2007b
Manufacturing of clay products occurs in
certain steps.
Activity: Create a poster or electronic
presentation of the steps in making a
specific product containing clay (perhaps
cat litter, toilets, paper, shoe polish,
medicine tablets, etc.) Identify the
constraints present at different stages of
the process.
Manufacturing usually involves a series of
steps, such as designing a product,
obtaining and preparing raw materials,
processing the materials mechanically or
chemically, and assembling, testing,
inspecting, and packaging. The sequence of
these steps is also often important. [6-8; 8.
The Designed World B. Materials and
Manufacturing]
Technological designs have constraints.
Some constraints are unavoidable, for
example, properties of materials, or effects
of weather and friction; other constraints
limit choices in the design, for example,
environmental protection, human safety,
and aesthetics. [5-8; Science and Technology
Content Standard E, Understandings about
Science and Technology]
Although weathered rock is the basic
component of soil, the composition and
texture of soil and its fertility and resistance
to erosion are greatly influenced by plant
roots and debris, bacteria, fungi, worms,
insects, rodents, and other organisms. [6-8;
4. The Physical Setting, C. Processes that
shape the Earth]
Soil consists of weathered rocks and
decomposed organic material from dead
plants, animals, and bacteria. Soils are often
found in layers, with each having a different
chemical composition and texture. [5-8,
Earth and Space Science Content Standard
D, Structure of the Earth System.]
The environment may contain dangerous
levels of substances that are harmful to
human beings. Therefore, the good health of
individuals requires monitoring the soil, air,
and water and taking steps to keep them
safe. [6-8; 6. The Human Organism E.
Physical Health]
Natural environments may contain
substances (for example, radon and lead)
that are harmful to human beings. [5-8;
Science in Personal and Social Perspectives,
Content Standard F, Personal Health.]
Scientists are linked to other scientists
worldwide both personally and through
international scientific organizations. [6-8; 7.
Human Society G. Global Interdependence]
Scientists have ethical traditions. Scientists
value peer review, truthful reporting about
the methods and outcomes of
investigations, and making public the
results of work.. [9-12; History and Nature
of Science Content Standard G, Science as a
Human Endeavor]
Clay scientists interact professionally
through many different scientific
organizations. These professional
organizations publish scientific papers and
reports.
Activity: Visit the web sites of different
societies for clay scientists (Clay Minerals
Society, Soil Science Society of America)
Automation, [especially] the use of robots,
has changed the nature of work in most
fields, including manufacturing. As a result,
high-skill, high-knowledge jobs in
engineering, computer programming,
quality control, supervision, and
maintenance are replacing many routine,
manual-labor jobs. Workers therefore need
better learning skills and flexibility to take
on new and rapidly changing jobs. [6-8; 8.
The Designed World B. Materials and
Manufacturing]
Women and men of various social and
ethnic backgrounds--and with diverse
interests, talents, qualities, and
motivations--engage in the activities of
science, engineering, and related fields such
as the health professions. Some scientists
work in teams, and some work alone, but all
communicate extensively with others. {5-8;
History and Nature of Science Content
Standard G, Science as a Human Endeavor.
People wanting to work in clay-science
related fields need certain math, science,
and technology skills.
Activity: Investigate the skills needed to
work as a clay scientist in different
settings. Investigate other jobs related to
clays. Visit the "Ask-A-Clay-Scientist"
website and read the biographies of the
featured clay scientists.
Because of the way soil forms, distinct zones
often occur, called horizons. Different soil
horizons may include mostly organic
matter, mixtures of clay, silt, or sand, or
materials derived from the bedrock.
Activity: Investigate a soil profile. Chart
the different layers and their
compositions/ characteristics.
People previously made things with
asbestos because it resisted burning (pipe
insulation, floor tiles, building materials)
before they found it was harmful to the
lungs. There are safety regulations that
protect people from products that contain
asbestos.
Activity: Research information on asbestos
and create a web of related ideas.
Table 3. Suggested Clay Science Activities for Middle School Students Linked to Standards
Standard from Benchmarks for Science
Literacy
Standard from National Science
Education Standards
Clay Concept and Suggested Activity
Waste management includes considerations
of quantity, safety, degradability, and cost.
It requires social and technological
innovations, because waste-disposal
problems are political and economic as well
as technical. [9-12; 8. The Designed World B.
Materials and Manufacturing]
Natural ecosystems provide an array of
basic processes that affect humans. Those
processes include maintenance of the
quality of the atmosphere, generation of
soils, control of the hydrologic cycle,
disposal of wastes, and recycling of
nutrients. Humans are changing many of
these basic processes, and the changes may
be detrimental to humans. [9-12; Science in
Personal and Social Perspectives Content
Standard F, Environmental Quality.]
Clays are used in waste management
because of their properties of
impermeability (they form a barrier to
contain wastes) and because they can absorb
some harmful chemicals or substances.
Clays have the ability to exchange cations
and thereby remove some contaminants
from water.
Activity: Investigate how clays are used in
landfills and water treatment.
Atoms often join with one another in
various combinations in distinct molecules
or in repeating three-dimensional patterns.
An enormous variety of biological,
chemical, and physical phenomena can be
explained by changes in the arrangement
and motion of atoms and molecules [in
crystals]. [9-12, 4. The Physical Setting D.
The Structure of Matter]
The physical properties of compounds
reflect the nature of the interactions among
its molecules. These interactions are
determined by the structure of the molecule,
including the constituent atoms and the
distances and angles between them. [9-12;
Physical Science Content Standard B,
Structure and Properties of Matter]
The physical properties of clays are a
reflection of their chemical composition and
crystal structures.
Some clays disperse easily in water and
absorb cations. Changes in the chemistry of
the water can affect the flocculation of clays.
Activity: Investigate dispersion,
absorption, and cation exchange of
swelling clay
Table 4. Suggested clay science activities for high school students linked to standards.
work. Through these actions, they refine their ideas of
how the world works. Early childhood science activities
provide children with materials, events, and ideas that
build a foundation for later science learning. Worth and
Grollman (2003) suggest that the following are essential
characteristics of a high-quality early childhood science
program: (a) activities build on children's prior
experiences, backgrounds, and theories of how things
work; (b) children's curiosity is encouraged as children
pursue their own questions about the topic; (c) children
are engaged in in-depth exploration over time in a
carefully prepared environment; (d) children reflect
upon, represent, and document their experiences and
discuss these with others; (e) science is integrated with
other domains and embedded in children's work and
play; and (f) all children participate in science. Teachers
support science inquiry by choosing the focus for inquiry
experiences, learning as much as possible about the
topic, providing materials, scheduling time for inquiry,
encouraging questions, fostering curiosity, observing
young students, and assessing learning.
Table 1 shows the related standards, and a third
column provides suggested opportunities for young
children to explore interesting clay-related topics.
Children delve into components of the natural world as
they work with mud, clay and sand. Children practice
science process skills as they make observations with a
hand lens of the visible components of mud. They might
plan and try new investigations such as determining the
effects of smearing mud, adding more water, waiting for
mud or clay to dry, and flexing dried mud. They might
collect mud samples smeared on paper, organizing the
collection (perhaps by color or components) on a bulletin
board, accompanied with drawings of the places from
which they were collected. Experimenting with damp
clay provides opportunities for increasing descriptive
vocabulary words (House, 2007) such as shape, bend,
coil, twist, pinch, smooth, rough, flat, bumpy, and thick.
A comparison of sand and clay provides strong contrast
that highlights the rheology of damp clay.
These investigations of mud, sand and clay provide a
foundation for learning about household products made
with clay, such as ceramic dishes, flowerpots, tiles, and
toilets. Households with cats, 34% of all American
households (American Pet Products Manufacturers
Association, 2003-2004), probably have litter boxes
containing swelling clay, or smectite. Experiments with
adding various amounts of water to smectite lead to
discovery of the gel-like properties of smectites. Many
other common items containing clay make use of this
property, such as wall paint, toothpaste, deodorant, and
lipstick. Primary grade students enjoy creating a display
of images of clay products (drawings, photographs,
Internet pictures) and classifying the products.
Young children learn by doing. Making a pinch pot
of damp clay or using a wheel to produce a round pot
provides an authentic setting for learning by organizing
the steps in a process. When the Talents Unlimited skill of
planning (Schlichter and Palmer, 1993) is used to guide
the plan for making a clay pot, students first label the
plan with the name of the project; list all the materials
and equipment needed; determine the steps needed for
the project and put them in order; think of problems that
were encountered; and finally, make changes to improve
the plan, avoiding or solving the problems. This
planning process allows students to note how tools are
used to help make things.
Clay Science for Intermediate and Upper Elementary
Students - Table 2 shows clay concepts appropriate for
intermediate and upper elementary students. Students at
this level are able to grasp the abstract concept of what
extreme magnification can reveal about the crystalline
nature of clay minerals and otherwise invisible features
of other items such as insect bodies. There are many
stunning books of scanning electron photographs (SEM)
(e.g., Bourély, 2002) and many Internet sites that feature
SEM photographs of such things as Kosher salt, a
housefly foot, a staple through paper, and Velcro (e.g.,
Boston Museum of Science, 2006). Images of kaolinite
(e.g., Kugler, 1998) or other crystals of clay minerals can
also be obtained from the Internet. An interestgenerating introduction to SEM photography is to post
four or five images and ask students to examine them
and guess what each image depicts. A creative twist on
this activity is to ask students to suggest humorous
possibilities for the same pictures. Be sure to draw
student attention to the crystal shapes suggesting an
outward consequence of the crystalline nature (and
therefore inward symmetric arrangement of atoms) of
Rule and Guggenheim - A Standards-based Curriculum for Clay Science
261
clay minerals and that they form as new minerals of
small crystal size rather than ground-up particles of
larger grains.
Objects made from dried clay (or "greenware") can
be compared against objects made from fired clay. Fired
clay involves a transformation of the clay minerals to
phases that have different properties (e.g., hardness,
electrical insulation). Activities where greenware is
compared to clay objects that have been fired or to
materials that contain clay, such as cups (plastic, paper),
or to materials that contain clay reinforced with lint
fibers may be evaluated for crack formation. These
activities allow students to organize results with graphic
organizers such as concept webs and charts. Research
shows that students who organize information learn it as
well as those instructed to learn the information in the
same time frame (Masson and McDaniel, 1981). Graphic
organizers are particularly effective for helping students
locate information (Robinson and Skinner, 1996)
comprehend content (Horton, Lovitt, and Bergerud,
1990), and write integrated essays (Robinson and
Kiewra, 1995).
Elementary-level students begin to build the
foundation for understanding soil as a living community
of organisms by examining soil samples and profiles,
identifying the macroscopic organisms that are present.
An illustrated poster presentation of such an
investigation is one way to share results with others.
Gibb (2000) described several engaging activities where
elementary-level students investigated soil. They
learned about pore spaces by pouring water into a jar full
of marbles, examined roots identifying root hairs, made
daily observations of red worms composting vegetable
leftovers, germinated kidney bean seeds in various
positions and noted the direction of root growth, and
wrote their interpretations in daily journals.
Students can investigate transport and deposition of
clays through simple experiments that compare the
suspension, transport, and settling of particles of sand,
silt, and clay. Because of the platy shape of clay particles
that have settled, they tend to cling to each other and
resist becoming dispersed in water or air, whereas fine
sand or silt are blown or washed away easily.
Additionally, air/water movement at the clay-water or
clay-air interface is nearly zero because of friction and
particle size. However, once dispersed, the relative large
surface areas of clay particles tend to keep them in
suspension.
An important aspect of science is its record of human
accomplishment. Through a study of the history of
science, students can begin to understand and appreciate
the contributions of diverse people to the development of
scientific ideas, inventions, and innovations that they
now enjoy and take for granted. A study of the history of
ceramics reveals the many ancient cultures that created
different types of pottery styles and techniques along
with the impact that pottery had on their lifestyles. An
interesting project is to make a timeline of ceramics by
printing images of different ceramic innovations from an
Internet image search and arranging them in order with
dates and titles.
Clay Science for Middle School Students - In middle
school and junior high school, students often enroll in an
Earth science class that presents, among other topics,
mineralogy and petrology. Clay minerals play a large
role as major constituents and cements in sedimentary
rocks, as foliated minerals in metamorphic rocks, and are
262
present, most notably as micas, in igneous rocks.
Identifying minerals by physical properties and
classifying rocks by mineralogy and grain size are
important activities.
Middle school students are ready to build upon their
previous understandings about clay to associate mineral
properties and features of the layered atomic structure
with industrial uses. Dubey and Rule (in review)
describe several effective activities for teaching middle
school students about the role of clays in various
products.
Middle school students are able to explore concepts
relating to soils in greater depth than younger students.
Soils are important for crop production, plant growth,
decomposition of wastes, storage of nutrients, filtering of
groundwater, and gas absorption / production. Soils are
the home of a vast community of organisms, provide raw
materials for construction, art, and medicine, and
provide information on human, climatic, and geologic
history. A detailed protocol for characterizing soil
horizons is available online from the Global Learning
and Observations to Benefit the Environment (GLOBE)
Program (2001). The GLOBE program (2006) is
particularly effective because it provides access to
environmental data from around the world via the
GLOBE website and the opportunity for students to
generate and contribute data to this site for scientists.
Teachers can obtain professional development
preparation for participating in GLOBE by attending free
workshops. Landa (2004) noted that many current
textbooks
describe
the
outdated
podzolpedalfer-pedocal-laterite system, ignoring the new
system. The new system consists of eleven soils based on
observable and measurable soil features. He suggested
that students consider the dynamic properties of soils,
many of which depend upon clay content: ion exchange,
shrink-swell behavior, nutrient cycling, and water
movement.
Career awareness, an important aspect of science
education, needs to be implemented early so that
students can prepare for their future careers by taking
appropriate courses in high school. One way for students
to learn about the jobs of clay scientists is to visit the "Ask
-A-Clay-Scientist" website (Rule and Kogel, 2003), which
is sponsored by the Clay Minerals Society. Biographies of
a diverse group of six clay scientists are shown. Students
can investigate the services offered by membership in
professional societies by browsing clay science society
websites.
Clay Science for High School Students - High school
students have sufficient background to explore the
chemistry and crystal structures of clay minerals to
understand their unique atomic arrangements, ion
exchange properties, and colloidal interactions that lend
themselves to many industrial applications.
Several activities that involve the crystal structures
and chemistry of clay minerals are found in a book on
teaching clay science (Rule and Guggenheim, 2002).
Kogel and Rule (2002) presented an exercise where
students assume the role of a mining company
exploration team to analyze a kaolin deposit. They
examined data such as SEM photographs, x-ray
diffraction patterns, maps, geologic cross-sections, and
reports of crude and processed properties of kaolin at
different drill-hole sites. Students are asked to write a
report on how to grade the clay in terms of proposed end
use; prepare cross-sections showing where each grade
Journal of Geoscience Education, v. 55, n. 4, September, 2007, p. 257-266
Major Clay Concept
The composition and origin
of clays.
Clay properties and their use
in products.
Soil components, structure,
and support for life.
Research in Student Thinking Related to these Concepts
Rule, Cavanaugh, and Waloven (in review) found that the majority of preservice elementary teachers
were familiar only with ceramics as clay products, with less than half aware that clays were naturally
occurring materials. Responses of preservice teachers who guessed the origin of clay minerals were very
similar to those who claimed to have been previously taught this information or who said they had heard
it from a reliable source. Scientifically inconsistent ideas about clay minerals expressed by preservice
teachers included: clay minerals form by a mixture of particles with water; pressure, heat, and/or melting
are needed for clay mineral formation; clay minerals are pulverized rock; clay minerals have an organic
origin; and clay minerals formed at the beginning of Earth or formed at the Earth's core. Rule, Cavanaugh,
and Waloven found that work with hands-on clay products and cards that listed properties helped
preservice teachers make significant gains in knowledge of clay's role in manufactured items as shown by
posttest compared to pretest scores.
Several investigators (Driver, Squires, Rushworth, & Wood-Robinson, 1992; Happs, 1982, 1984; Russell,
Bell, Longden, & McGuigan, 1993) researched children's ideas about soil. Many children believe that soil is
made of dirt or any sort of material occurring in the ground; it is brown and homogenous with leaves,
twigs and stones mixed in but not an integral part; it is unchanging and does not contain air. Children
held various conceptions about the age and depth of soil. Soil may be only a few years old or as old as the
Earth; soil depth can be as much as ten miles. Some children believe that most land is soil within which
may be found masses of rock.
Libarkin, Anderson, Dahl, Beilfuss, and Boone (2005) investigated college students' ideas about the Earth.
One idea from their research supports the children's idea that most land is made of soil or dirt: "...
students were unsure about the location of the Earth's tectonic plates, believing them to be somewhere
below the Earth's surface, with empty or dirt-filled space between the tectonic plate and the Earth's
surface" (p. 23). Another interesting example taken from this same investigation showed that some
students believed a source of earthquakes was "exploding soil" (p.23).
Leach, Driver, Scott, and Wood-Robinson (1996) explored children's ideas about the cycling of matter in
soils. They found that students, even at the age of 16, were unable to relate the processes of
photosynthesis, respiration, and decay into a view of the cycling of matter in ecosystems.
Clay's role in the rock cycle.
Several researchers have investigated K-12 and college students' conceptions of rocks.
Driver, Squires, Rushworth, and Wood-Robinson (1994) reported New Zealand children's ideas about
rocks and clay. These children generally recognized rocks as heavy, hard, jagged masses of homogeneous
material, applying the word to both rock and mineral specimens and items made of natural materials such
as brick. The children in the study were unaware of the classification of sedimentary particles by size and
so classified boulders, gravel, sand and clay by the place of origin. A piece that had rolled down a hillside
was called a boulder, gravel was used to describe loose material at the edge of a road, sand was associated
with beaches and deserts, and clay was sticky orange-colored material found underground.
Kusnick (2002) examined preservice teachers' ideas about rock formation, finding that many believed that
rocks "grew" as more sediment stuck to them, that humans were involved in rock formation by causing
weathering and transport, that sedimentary rocks form as puddles dry, rocks are formed where they are
found and generally form by catastrophic events such as floods and earthquakes.
(Ford, 2003) surveyed sixth graders and found that most students did not grasp the purpose of learning
about the rock cycle. They perceived that the rock cycle was the cause of rock formation, rather than a
model showing relationships among rock categories and their formation.
Clay scientists
Students' mental images of scientists have been examined through the Draw-A-Scientist projective test for
over fifty years (Finson, 2002). The more stereotypical a students' image, the less likely that student is to
select science coursework and enter a science-related career (Hammrich, 1997). Stereotyped images
generally portray scientists as male Caucasians working indoors with chemistry equipment wearing lab
coats, eyeglasses, and facial hair. Students who draw scientists of the same gender, ethnicity, and
characteristics as themselves can picture themselves as scientists. Such students are more likely to pursue
coursework leading to a career in science (National Science Teachers' Association, 1992, 1993). Several
studies have found that students with multiple exposures to scientists along with other interventions
reduced the number of stereotyped characteristics in their drawings (Bodzin & Gehringer, 2001; Finson,
Beaver, & Cramond, 1995; Flick, 1990; Mason, Kahle, & Gardner, 1991; Smith & Erb, 1986). Rule,
Cavanaugh, and Waloven (in review) examined drawings of scientists and of clay scientists made by
preservice elementary teachers before and after participation in a science methods course that included a
unit on clay science. They found that pretest scientist drawings exhibited traits found in other studies with
posttest drawings showing fewer stereotypes. In contrast, pretest drawings of clay scientists showed more
casual attire and outdoor settings with clay scientists pictured with clay, ceramics and potters' wheels.
Posttest drawings included more female clay scientists and some clay scientists of color, with a larger
variety of clay products (plastics, paint, cosmetics, paper, pharmaceuticals) shown.
Table 5. Summary of major clay concepts for K-12 students and research in students' conceptions related
to these ideas.
occurs, and propose how to separate the deposit into
mineable benches. Parekh and Rule (2002) described a
lesson presented as a learning cycle in which students are
confronted with the discrepant event of adding "mud"
(perfume-free clumping cat litter ground to a powder) to
purify "wastewater" (water with latex paint added).
Students then explore colloidal chemistry interactions to
understand the cleansing of the water. Ross and
Guggenheim (2002) provided several activities for
exploring interlayer reactions in smectite that involve
Mg cation exchange, glycerol solvation, and an
intercalation reaction with a blue color change.
There are other simple and interesting experiments
for investigating clay chemistry (e.g., Guggenheim, 1997)
in a book for teaching mineralogy published by the
Mineralogical Society of America. Sources for clays used
in these experiments are noted at the end of this article.
Students may investigate clay dispersion by comparing a
very sandy soil sample with swelling clay (smectite). Fill
two thirds of each of two 150 mL. glass beakers with
water, adding about three tablespoons of the solid to
each. Stir only the soil/water mix. Allow both beakers to
stand for two or more days, with students making daily
observations. The solids of the soil/water mixture will
settle to the bottom, but the unstirred clay particles will
disperse. As time passes, the montmorillonite will form a
relatively large clump of hardened clay (clay plus
Rule and Guggenheim - A Standards-based Curriculum for Clay Science
263
interlayer H2O) many times the volume of the initial
three tablespoons.
Clay adsorption can be demonstrated by adding a
methylene blue solution (containing an organic molecule
with an associated positive charge, some molecules in
food coloring may have a positive charge and may be
substituted for methylene blue) directly to a beaker
holding montmorillonite mixed with water. The clay
adsorbs the dye very quickly, illustrating the ability of
montmorillonite to adsorb other materials, and thus act
as a "filter" for groundwater contaminants.
The effect of cation exchange (i.e., a change in
chemistry of cations associated with the clay structure)
on the physical properties of the clay is illustrated in this
last example. Place one tablespoon montmorillonite into
each of three beakers. Add 30 mL of a saturated solution
of NaCl, stir thoroughly, and set aside. Repeat the same
procedure for clay plus MgCl2 solution and clay plus
CaCl2 solution. Allow each beaker to stand about five
minutes until most of the clay settles to the beaker
bottom. The fluid may remain murky. Generally, the
high salt content of the fluid prevents dispersion. Then,
remove most of the salt by decanting the fluid from the
clay, being careful not to lose much clay. Add water to
the clay residual so that it is at the 60 mL. level on the
beaker, stir, and allow the clay to settle again. Repeat the
procedure a second time. Cation exchange occurs
immediately upon stirring the montmorillonite in the
saturated solutions of NaCl, MgCl2, or CaCl2. The
Na-exchanged clay contains H2O in the interlayer also,
and does not settle as the Mg- or Ca-exchanged
montmorillonites settle after stirring. However, with salt
removal, the Na-exchanged montmorillonite will
disperse. This effect is more pronounced with additional
washings.
EVALUATION OF THE SUGGESTED CLAY
CURRICULUM
Two recent studies have implemented and evaluated
parts of the curriculum outlined in this article with
positive results. In the first study (Dubey and Rule, in
review), twenty-one seventh graders participated in a
week of lessons focused on the use of clay in products,
one of the key clay concepts for middle school students.
Student scores on an assessment testing knowledge of
products containing clay, ceramics terms and processes,
and clay's role in products improved significantly from a
pretest mean of 52.5% to a posttest mean of 82.5%.
Students reported that they learned much and enjoyed
the activities; the instructor found that all students were
engaged and successful in contrast to other units of study
that year.
A second study (House, 2007) examined the growth
in vocabulary of twenty-one preschoolers as a
consequence of participation in six clay-related lessons in
which students manipulated both artificial clay materials
and potter's clay, culminating in the making, glazing,
and firing of pinch pots. Mean pretest scores on an
assessment requiring students to demonstrate with clay
vocabulary words such as "bend," "roll," "coil," and
"twist," were 50% with a mean posttest score of 81%.
Students thoroughly enjoyed their work with clay and
were pleased to demonstrate their new knowledge on
the posttest. In general, children added from two to three
new words to their speaking vocabularies, as measured
by an assessment in which the children were asked to
verbally describe damp / dry clay and unglazed / glazed
ceramics.
These examples show the utility of selected parts of
this standards-based clay curriculum for students at two
levels. The first author (A. Rule) has taught additional
REVIEW OF THE LITERATURE ON K-12
parts of the curriculum to first and second graders, but
STUDENTS LEARNING ABOUT CLAY
these lessons were not formally evaluated. Additional
formal studies may provide evidence for the efficacy of
Table 5 summarizes the status of research concerning the entire curriculum.
students' ideas about the five major conceptual areas of
clay addressed in this paper.
SUMMARY AND CONCLUSION
In contrast to the few studies focusing on students'
ideas about clay, many researchers have investigated We have examined the usefulness of using clay concepts
ideas of students relating to soils and cycling of to teach aspects of physical, chemical, and Earth sciences.
materials, but with little information about children's We have divided the preK-12 curriculum into four
ideas of clay's role in soils. Students' conceptions of rocks grade-level parts and have identified clay concepts that
have also been examined by several investigators, but support other science learning suggested by national
with little attention in particular to clay's role in the rock standards at these levels. We have also examined what is
cycle. Finally, students' conceptions of scientists in known about student (and adult) thinking regarding
general have been studied for over fifty years with the clay concepts, indicating the need for more research into
consensus of research indicating that people of different this area. Two preliminary studies have shown the
genders, races, and countries hold very similar efficacy of specific parts of this curriculum. Because
stereotyped ideas as promoted by the media. In misconceptions persist after instruction and because
particular, the image of a scientist is a white male with effective practice of new learning may prevent students
glasses and facial hair in a lab coat who is amoral (in from reverting to previous non-scientific ideas, it is
contrast to immoral), obsessive, insensitive (Schibeci, important to identify successful teaching techniques.
1986), or distinctly brilliant, and unsocial (Rampal, 1992). There is ample room for further research in this area with
The good news is that efforts to expose students to real regard to clay science education.
scientists have been successful in reducing stereotyping.
Similarly, a recent study (Rule, Cavanaugh, and SOURCES OF SWELLING CLAY
Waloven, in review) comparing preservice elementary
teachers' drawings of scientists and clay scientists before Cat litter material suitable for clay experiments (R.
and after a science methods course that included a unit Brown of Wyo-Ben, Inc., personal communication) is a
on clay science indicated that stereotyped mental "clumping" cat litter; is unscented; and is without color or
conceptions changed as a result of the course activities. deodorizer additives. Some products that should meet
these criteria are Integrity Cat Litter, Litter Purrfect,
264
Journal of Geoscience Education, v. 55, n. 4, September, 2007, p. 257-266
Snuffy's Kitty Klean, Booda Ultra Clump, and Everclean
unscented. There are other additional products not listed
here. However, cat litter is often not of sufficient purity
for many clay experiments.
Swelling clay (montmorillonite) may be obtained as
Voclay® or "unmodified" Supergel®, available from
American Colloid Company, 1500 W. Shure Dr.,
Arlington Heights, IL 60004, USA. A gallon of
unmodified Supergel® or Voclay® will last for years. In
the past, American Colloid has provided these quantities
free of charge as a service to the educational community,
but please offer to purchase the material. Alternatively,
Sigma-Aldrich Chemical Company, P.O. Box 14508, St.
Louis, MO 63178, sells smectite under its rock name,
bentonite (B 3378), in 2.5 kg quantities. Consult
www.sigma-aldrich.com for current prices.
ACKNOWLEDGEMENTS
The Petroleum Research Fund of the American
Chemical Society is gratefully acknowledged for partial
funding of this research under grant #43871-AC2..
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