TITLE: Does it Rot or Not? Using Archaeology to Explore Decomposition
By Amy Margaris (margaris@email.arizona.edu) and
Sara Chavarria
OBJECTIVES:
Students will be able to differentiate between materials that will decompose and those
that will not, by learning from modern and archaeological examples. They will learn to
use the concepts of organic versus inorganic to explain why materials do or do not
decompose with time. Different rates of composition can be explored by discussing
bones and shells, which are organic but decompose very slowly. This exercise can be
used to complement classroom projects about decomposition, recycling, the life cycle, or
the food chain.
STANDARDS:
3SC-F1: Identify occupations that require the application of science and technology.
4SC-F7: Explain the interaction of living and non-living components within ecosystems.
1SS-E2: Describe the legacy and cultures of prehistoric American Indians in Arizona,
including the impact of, and adaptations to geography.
BACKGROUND INFORMATION:
Archaeologists study how people lived in the past by analyzing the various traces they
left behind. The question of what materials preserve in the archaeological record is a
crucial one to archaeologists. While we’d like to study every possible trace of past human
activities, many types of artifacts are rarely discovered because they do not survive the
test of time. As a rule of thumb, artifacts made from “organic” materials tend to
decompose with time, while those made from “inorganic” materials preserve well, and
make up most of what archaeologists generally find when they excavate. We use
“organic” to refer to items that are made from things that were once living. Organic
items include wood products, plant fibers, grain and other food remnants, cloth and
textiles, basketry, animal hide, and sinew. Inorganic items are made from things that
were never living, such as clay, brick, plastic, metal, and glass.
Bones and shells form a special category because they come from living beings, and
in that sense are organic. Part of their composition is mineral, however, which makes
them very hard and resistant to decay. They do decompose with time, but much more
slowly than do other organic materials.
Because not all artifacts preserve equally well, archaeologists must fill in a lot of gaps
when they try to reconstruct the ways people lived in the past. In some cases, evidence of
entire activities may be lost. The archaeological record is more of a cracked mirror than
a perfect reflection of the past. This means there is lots to be left to the imagination, but
also lots of room for future research and learning!
PREP TIME:
Day Before:
photocopy handouts
make overheads
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print word bank key and artifact collage key for teacher reference
divide poster board into 2 columns labeled “Organic Materials” and “Inorganic
Materials”
Optional: make Modern Matter illustrations into a set of 8 laminated cards
TIME LINE:
Procedure: 1+ hours
Application: 1 hour
Assessment: 1 hour
TOTAL TIME: 3+ hours
MATERIALS NEEDED:
1. Handout 1: Modern Matter p. 1
2. Overhead 1 OR Modern Matter Cards 1-4
3. Handout 2: Modern Matter p. 2
4. Overhead 2 OR Modern Matter Cards 5-8
5. Overhead 3: The Jacket
6. Handout 3: Artifact Collage Exercise
7. Handout 4: Text to Artifact Collage Exercise
8. Handout 5: Amy the Archaeologist Assessment
9. Word bank key
10. Artifact collage key
11. Poster board for word bank
12. Crayons to color handouts
13. Optional: Overheads of real archaeological artifacts
VOCABULARY:
decompose
decomposition
tool
material
organic
archaeology
inorganic
archaeologist
mineral
artifact
ACTIVITY:
Setting the Stage
Introduce or review the topic of decomposition. To decompose = to rot. All living
things (plants and animals) are organic, which means they are alive, grow and die.
Eventually, all organic materials decompose because they are eaten by tiny organisms
living in the ground, by animals, or even by humans as food. In the meanwhile,
humans can make many useful tools out of organic products. Many other tools people
use are made from things that were never alive, and do not change much through time.
Things that were never alive are called inorganic, or not organic. Inorganic materials
do not decompose.
Today you will learn about what is organic and inorganic in our world by thinking like
an archaeologist.
Introduce the subject of archaeology and the role of archaeologists: e.g., Archaeologists
are scientists who learn about people who lived a long time ago by studying the objects
(artifacts) they left behind.
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Procedure: Modern Matter: Does it Rot or Not?
PART I
1. Give each student a copy of Handout 1 and display the matching overhead
(Overhead 1).
2. Go over each image with the students, helping them to movie from object to
material, and decide if materials are organic or inorganic.
3. As you go, write each material (food, bone, clay, plastic, paper) on the poster board
under “Organic Materials” or “Inorganic Materials” to make a word bank. This will
be useful to students during the subsequent exercises. (See the provided key.)
4. Give students the second page of the exercise, Handout 2, and display the matching
overhead (Overhead 2). Have each students fill in their own sheet this time,
consulting their neighbor if they need help.
5. When the students have finished, go over the handout and add the new set of
materials (metal, glass, wood, stone) to the word bank poster.
6. OPTIONAL: Some students may argue that bones like the chicken leg are inorganic
because they can be found even when the rest of an animal has rotted away (as they may
have seen in cartoons, horror movies, or during a walk in the woods). If desired, the
teacher can present a brief discussion here about different rates of decomposition, which
explains this phenomenon.
Time-Out Discussion: The Mystery of the Bones
All bones come from something was once alive. Remember, they are inside of us right
now! Even when animals die, their bones can stay around for a long time. The same is
true of seashells, which are like bones on the outside, of an animal rather than the inside.
Animals make bones and shells to protect their soft bodies from getting hurt. Bones
and shells are very hard, like armor. When animals die, they begin to decompose. They
are eaten by other animals, or by tiny organisms in the ground that are too small for us to
see with just our eyes. These tiny organisms eat bones and shells, but it takes a very long
time because they are so hard. That is why bones and shells often stay in the ground for
so long, where archaeologists can find them.
Question: Do bones and shells rot? Answer: Yes they do – it just takes hundreds of
years!
PART II
6. Display Jacket overhead (Overhead 3) and fill in the blanks with the help of the
class.
7. Ask the class to have a look at their own clothes. Have them raise their hand and
offer what parts are organic (cloth, leather, thread, etc.) and what parts are inorganic
(metal zipper, plastic button, etc.). Are they wearing any materials that haven’t been
mentioned so far? If so, help the students figure out what they are made from, so
they can determine if the materials are organic or not. Add these materials to the
word bank poster.
Application: Old Artifacts: Do They Rot or Not?
Archaeologists look for artifacts in the ground to learn about the people who left them
there long ago. Artifacts help archaeologists learn about what people ate, what they
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wore, and how they lived. You are now experts in decomposition, and an archaeologist
needs your help!
We will be looking at pictures of some tools that were left behind by people hundreds
of years ago. We must decide which parts of the tools archaeologists will probably find
because they are inorganic, and do not decompose. Which parts are organic, and will
probably decompose?
2. Pass out Handouts 3 & 4 (Artifact Collage and the accompanying text).
3. Work as a class. Have students take turns reading the items on the sheet aloud,
while the class circles the appropriate parts of the pictures. (See the provided key.)
Students can use the word bank poster to help them decide which materials are
inorganic.
Optional: The teacher can display images of real artifacts on the overhead projector
during the exercise.
Optional: The teacher can make a second copy of the Artifact Collage sheet. After
finishing the first sheet, students can repeat the exercise but circling what WILL rot.
(What archaeologists WILL NOT find in 500 years.)
4. Have students give an appropriate title to their collage sheet, such as: “These
Things Do Not Rot Because They Are Not Organic”.
5. Students can spend time coloring their sheets.
Assessment
Meet Amy the Archaeologist! Amy has gotten permission to look for artifacts, and has
brought along her tools to help her dig up the artifacts and carefully study them. What
has she brought that will someday rot, and what will not rot?
1. Have students fill in the sheet on their own, using what they have learned in the
previous exercises. [10 questions]
Optional: Allow students to consult the word bank poster for help.
2. Students can color in the sheet if they have extra time.
Closure
Suggestions are welcome!
ADDITIONAL RESOURCES:
http://www.astc.org/exhibitions/rotten/rot.htm (more about how things rot)
http://www.findarticles.com/cf_dls/m1590/13_57/73537927/p1/article.jhtml
(decomposition activity)
http://www.offwell.free-online.co.uk/decompos.htm (Photographs capture the
decomposition of an animal carcass. This one is graphic.)
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