material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Breaking Things:
Lecture/Demonstration/Lab Activity
Developed by: Michelle Robinson, Teacher (michelle.c.rob@gmail.com) and
Coralee McNee, Teacher (coralee.m@gmail.com)
Table of Contents
Overview........................................................................................... 1
Science Standards Addressed .......................................................... 1
Goals/ Objectives ............................................................................. 2
Materials and Equipment .................................................................. 2
Key Vocabulary Words ..................................................................... 2
Safety ............................................................................................... 3
Procedure (total estimated time- 1 hr)............................................ 3
Assessment Examples: (answers in parenthesis) ............................. 5
Locating Materials ............................................................................ 6
Background Information ................................................................... 7
References........................................................................................ 7
Student Worksheet .......................................................................... 7
Overview
This lesson discusses the basics of atomic structure, the arrangement of
neighboring atoms within a solid, and its relationship to the properties of
different materials as they break. The students illustrate this point by
breaking a paperclip, toothpick, plastic grocery bag, and ceramic tile.
Science Standards Addressed
U.3 Change, consistency, and measurement
U.5 Form and function
B.1 Properties and changes of properties in matter
B.2 Motion and forces
B.3 Transfer of energy
1/11
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Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
material science teachers’ aide
Bonding, Metals, Ceramics, Fracture
Goals/ Objectives
The students will be able to distinguish a metal, polymer, ceramic and
composite material. The students should be able to predict how an
object will break when they know the type of material used to make it.
The students should be able to name some properties of different classes
of materials. The students should understand that all objects are made of
atoms and that these atoms and how they are put together dictate their
properties.
Materials and Equipment
paperclip (class number)
plastic grocery bags (class number)
wooden toothpicks (class number)
ceramic tile (2)
tile cutter (1)
safety glasses (3)
heavy duty clear plastic bag (2)
hammer (1)
Key Vocabulary Words
Polymer- A class of natural or man made substances made from smaller
units called monomers arranged in long chains.
Ceramic- Compounds made from metals bonded with non-metals.
Ceramics are hard, and brittle. They are thermal and electrical
insulators. Glass is a special type of ceramic.
Metal- A material that is usually hard, shiny, solid, and ductile. Metals are
good conductors of heat and electricity.
Composite- A material made from a combination of two different
materials. Man made composites include fiberglass, and carbon fiber.
Ductile- Workability, materials that can easily be changed in shape.
Ductile materials can be rolled into sheets, drawn into wires, etc.
Brittle- Materials that are hard and cannot readily be changed in shape
without breaking
2/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Crystalline- A material with an orderly arrangement of particles, that
follow a repeating pattern.
Amorphous- A materials with a random arrangement of particles that do
not follow a repeating or predictable pattern.
Safety
Safety Goggles Required
Procedure (total estimated time- 1 hr)
Set-Up (5 minutes)
Put 1 paperclip and 1 toothpick in each of the plastic bags to make
student science kits.
During (45 minutes)
Begin with an introduction to the atom and the various forms atoms can
configure themselves in to make different materials. Define crystalline
and amorphous and draw examples or show structure models
Tie in the concept of crystals to the minerals that the students have
studied previously in class. Minerals are called crystals when the atoms in
them are in an orderly arrangement – a predictable, repeating pattern.
One of the jobs of geologists is studying what kinds of atoms are in the
rocks they are looking at and how those atoms are arranged. The type
and arrangement of the atoms can change how the material behaves or
change the material’s properties.
Ask the students to define some material properties. Describe the job of
a materials scientist. Materials scientists correlate the arrangement of
atoms to the properties of the material. They also tie together the
properties and arrangement with how to make materials, so if you want a
light strong bicycle you can ask a materials scientist what material you
would use to build your bicycle. One thing materials scientists do to learn
more about materials is BREAK THINGS! The way that a material breaks
gives clues about the type of material present and how the atoms are
3/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
arranged in it. Today we are going to look at breaking tile, paperclips,
toothpicks and plastic bags.
Describe that the ceramic tile is crystalline. Also the atoms within a
ceramic are bonded very tightly together. If the classroom was a ceramic
material and the students in the desks were sitting in rows and columns
holding hands really tightly, the students would represent the structure of
atoms within a ceramic material. Choose a volunteer, provide safety
glasses and gloves and have them swing a hammer into a ceramic tile so
the tile will shatter into several pieces in the heavy duty plastic bag.
If we look closely at the pieces, we will see that the tile broke in certain
directions more easily than others. This is because the material is
crystalline, which means the atoms are arranged in rows, and the tile
breaks more easily along the rows than across the diagonal of the crystal.
Compare it to trying to separate the desks in a classroom.
Since it looks like the tile wants to break in a certain way, let’s try to help
it out. If we score the tile, or start a crack in a certain place, and then try
and break it what do you think it will do? Now run the hand held tile
cutter perpendicular to one edge of the tile.
Get another volunteer to break the scored tile. Describe that the tile
preferred to break along one of the rows of the atoms. A ceramic is
made of groups of atoms that are arranged in orderly rows and columns.
The ceramic breaks without deforming. The word for this is brittle.
Ceramics are brittle.
So now let’s try breaking a paperclip. Ask the students what type of
material is in paperclips. Describe that metals are crystalline like the
ceramic tile, then ask if they think that the clips will break the same way.
Have everyone bend the paperclips back and forth until they break. Also
ask the students to count the number of full bends that they make before
the paperclip breaks. Discuss why they broke differently from the
ceramic tile (because paper clips are steel and the atoms in steel can slide
over one another more easily than in a ceramic; there is much more detail
4/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
in the ASM module, "Introduction to Steel"). The word to describe the
fact that the paper clip bends is ductile. Most metals are ductile.
Describe that the plastic bag is a polymer and that the atoms have an
amorphous “jumbled up” arrangement. Describe that the atoms are tied
together in chains and these chains are mixed up like spaghetti. Ask the
student how they expect the bag to break. Have everyone pull the bags
apart. Ask them to look at where the bags broke. Note that the white
part of the bag is where all the jumbled up atoms are trying to get in
better order – become more crystalline. Would you describe the plastic
bag as brittle or ductile?
Not only can you combine atoms to make different materials, but you can
combine different types of materials to make new structures. Instruct
the students to break their toothpicks.
Now you can see some parts of the toothpick sticking out farther than
others. This is because the toothpick is made up of long chain molecules
like the plastic, held together with a binder like glue. Since the toothpick
is made up of two different types of materials, it is called a composite
material. Ask the students if they know about any other types of
composites. There are many types of composites, some ductile, some
brittle.
The goal of this unit is for the students to see that atoms can be put
together in lots of different ways, which give materials lots of different
properties. We have studied in this unit the 4 basic types of materials—
metals, ceramics, plastics and composites. Materials scientists study how
to change the arrangements of atoms to get different properties.
After a question and answer session, pass out the attached quiz and then
correct the quiz as a class.
Tear-Down (10 Minutes)
5/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Place all unbroken items back into ‘science kits’. All broken items go into
the trash can. Collect science kits, and clean up any remaining ceramic
tile shards.
Assessment Examples:
(answers in parenthesis)
1. How many major classes of materials are there?
(4 classes of materials: Metals, Ceramics, Polymers, and
Composites.)
2. Can a material be made of the same atoms, but act differently than
another material also made of those atoms?
(Yes, the way the atoms are bonded or stuck together also affects
its properties.)
3. Does metal break in a ductile or brittle way?
(Ductile.)
4. Does ceramic typically break in a ductile or brittle way?
(Brittle.)
5. Can anyone think about what type of failure is most desirable in
engineering?
(Ductile failure is preferred so that catastrophic failure is avoided.
Catastrophic failures are those that occur without warning. As you
learned from bending your paperclip, the paperclip started to get
skinnier where the material was moving away from the bend
because it couldn’t handle the load. The ceramic tile didn’t have
this middle ground, but just snapped! That would be catastrophic!
Imagine if they made airplane wings out of ceramics instead of
metal.)
Locating Materials
Materials and supplies can be found in the chemistry lab and in local
stores, as needed.
6/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Background Information
Metals are strong and ductile, held together by metallic bonds made up
of electrons that are shared throughout the structure. This leads to
metal's electronic conductivity, reflectivity, strength and ductility.
Ceramics are strong and brittle. Ceramics are held together with strong
bonds either ionic or covalent. This leads to ceramics properties with a
lack of ductility or conductivity. Glass is a special type of ceramic, with
properties such that it is transparent. The structure of ceramics, and
metals, do not alloy any absorbency.
Polymers are made of covalently bonded strings of atoms; these atom
chains or strings are mixed in a very disordered or amorphous way. While
the bonds between the atoms within the polymer chain are strong, tight
bonds, the bonds betweens the polymer chains tend to be the weakest
bonds, known as Van der Waals or hydrogen bonds. Because the majority
of the polymer is made of these really long chains the bonds that we
interact with on a macroscopic level are the van der Waals bonds, which is
why polymers have their properties of pliancy (plasticity), softness and
low strength. Because polymers are ‘open’ structures, they can allow for
increased absorbency.
Composites are a combination of materials. Fiberglass is one example,
made of glass fibers and an epoxy matrix. However, there are lots of
composites that we use all the time—fabrics of different fibers, fiber
reinforced plastics, even wood, which is a composite of cellulose and a
binder.
References
Lots of information on materials and other science topics can be found at
http://www.newton.dep.anl.gov/askasci/mats05.htm
Definitions of brittle and ductile may be found in the encyclopedia or on
Wikipedia
7/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
What is a materials scientist?
http://www.newton.dep.anl.gov/askasci/mats05/mats05001.htm
Discussion on strong and weak materials:
http://www.newton.dep.anl.gov/askasci/mats05/mats05043.htm
A more in-depth discussion of ceramic properties (more for the teacher)
may be found at
http://www.virginia.edu/bohr/mse209/chapter13.htm
Acknowledgement
This module was developed by the ASM Foundation K-12 committee's
Middle School Task Force with input from teachers and staff and editing
assistance from Peter Kazarinoff, all of whose contributions are
acknowledged with thanks.
Copyright ASM International 2010; Permission is granted for
free use by instructors for educational purposes.
8/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Breaking Stuff
Name:
___________________________
Date:______________
1. All things are built from atoms . They are (large/ small)
and there are about ____100_____ different types of
atoms .
2. Crystalline and amorphous materials have atoms that
arrange themselves very differently. Draw a line between
the word that describes how these atoms are arranged
and the picture of what the atoms would look like.
Amorphous
Crystalline
3. Are crystals crystalline or amorphous?
(Circle one)
4. Materials are defined by their properties. Write three
properties:
9/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
___________________,
___________________
___________________,
5. Material properties are determined by the type of
____________ in the material and the way the
__________ are arranged.
6. The four types or classes of materials are
_______________, _______________,
_______________ and _______________.
7. Now that you know what a metal, polymer, composite,
and ceramic are- tell me what materials these objects are
made from:
Paperclip __________________________________
Floor Tile __________________________________
Toothpick __________________________________
Grocery Bag ________________________________
8. How many bends did it take to break your paperclip?
__________________
9. Types of materials (polymers, metal and ceramics) all
have different properties. Use one word to describe how
each of these materials broke.
10/11
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material science teachers’ aide
Unit: Properties of Matter
Subject: Materials Classification
Grade Level: 7 – 9
Key topics: Atomic Structure,
Bonding, Metals, Ceramics, Fracture
Paperclip __________________________________
Floor Tile __________________________________
Toothpick __________________________________
Grocery Bag ________________________________
Enrichment Activities
•
•
Have students draw in fracture surfaces in their lab notebooks.
Show SEM images of fracture surfaces and have the students guess
which SEM photo came from which material.
11/11
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