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Lesson: Life After Trash

(Lesson courtesy of Teach Engineering and the Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder). Grade Level: 7 (6-8).  Group Size: 2-4. Time Required: 90 minutes. Expendable Cost Per Group: US$ 1.

New life


Student teams use the engineering design process to create a useful product of their choice out of recyclable items and “trash.” The class is given a “landfill” of reusable items, such as aluminum cans, cardboard, paper, juice boxes, chip bags, egg cartons, milk cartons, etc. Each group is allowed a limited amount of bonding materials, such as duct tape, hot glue and string. The activity addresses the importance of reuse and encourages students to look at ways they can reuse items they would normally throw away. Students are further prompted to consider the problems with growing landfills, and efforts by engineers and others to reduce pollution, emissions, and trash production.

Learning Objectives

After this activity, students should be able to:

  • List harmful consequences of global warming.
  • Explain how recycling and reusing helps cut down on greenhouse gases.
  • List ways to reuse items before throwing them away.
  • Use the engineering design process to create a product from reused materials.

Engineering Connection

Engineering plays an important role in our environment. Our landfills are filling up faster and faster and pollution levels are getting higher and higher. Designing projects from a global perspective including low-energy manufacturing, renewable sources and utilizing recyclable and reusable materials is critical to decrease our pollution levels for a cleaner, healthier planet.


Colorado Science

Standard 5: Students understand that the nature of science involves a particular way of building knowledge and making meaning of the natural world. (Grades 0 – 12) [2007]

2. humans use renewable and nonrenewable resources (for example: forests and fossil fuels) (Grades 6 – 8 ) [2007]

For a list for other states, please check the TeachEngineering Website.


Materials List

Safety Issues

It is suggested that aluminum cans not be cut since their edges are very sharp. Some teachers may wish to omit them from the list of materials.

Each group needs:

  • duct tape, 12 inches (~30 cm)
  • string, 12 inches (~30 cm)
  • glue or hot glue gun

To share with the entire class:

  • aluminum cans (please see safety cuation above)
  • used copy/scrap paper
  • newspaper
  • used cardboard
  • egg cartons
  • (rinsed out) plastic bottles
  • chip bags
  • (rinsed out) drink boxes
  • other recyclable/used items of choice

Pre-Requisite Knowledge

A basic understanding of the engineering design process and completion of the TeachEngineering Global Climate Change lesson, or other similar introduction, if the teacher wishes for the students to have a good understanding of global warming. The Department of Environmental Protection resource, below, provides a number of excellent resources. Teachers may also wish to inspire their students’ sense of competition by having them enter the annual PBS Trash to Treasure competition. They can also read about the 2008 winner, 12-year-old Max Wallack, who designed the geodesic “Home Dome,” a temporary shelter for homeless persons built of recycled materials.

(image from
(image from


Our climate is changing as we speak, and within your lifetime, the Earth could become 2-4°F warmer. The Earth has already warmed by about 1°F during the past 100 years. Many scientists think this is due to our activities and impact on the planet, and they expect the average global temperature to increase an additional 2-6°F over the next one hundred years. While we do not know exactly what the result of these small changes in temperature might be, scientists have made some predictions. Rising temperatures could melt ice caps at the Earth’s poles, causing sea levels to rise, which in turn could cause flooding in coastal regions. Plants and animals in fragile ecosystems may find it difficult to adapt to warmer temperatures. And, people will have to get used to an increased number of hot days each year.


Fortunately, policy makers and engineers are taking precautions to try to slow down global warming. The release of greenhouse gases is an important thing to remember in engineering design. We need to be aware of how much pollution results from the manufacture of all the products that engineers design. Today, you will all be engineers responsible for designing a product entirely out of used items. How does this help keep pollution levels low? It helps save our resources — such as trees, oil and coal — that would be used to build a new product as well as puts fewer products in our landfills, which lowers the greenhouse gas caused by decomposing garbage.

How do we prevent the planet from overheating? We need to prevent greenhouse gases from being overproduced. Can you think of things we do every day that create greenhouse gas, such as carbon dioxide? (Possible answers: Driving our cars or using too much electricity made by fossil fuels. See the associated lesson for more ideas.)

Engineers can help us rethink the way we do these things so that we can reduce the amount of greenhouse gases we produce. For example, engineers are designing more efficient cars that use less gas and produce fewer greenhouse emissions. Engineers can also create products that can be reused more often, or they can create products using materials that have already been used by other people — just as you will do today.


Climate Change: The change in long-term weather patterns; changes can cause warmer or colder temperatures; annual amounts of rainfall or snowfall can increase or decrease.

752410_windmills_and_yellow_fieldGlobal Warming: Refers to an average increase in the Earth’s temperature, which in turn causes changes in climate; a warmer Earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans.

Greenhouse Effect: The effect produced as greenhouse gases allow energy from the sun to pass through the Earth’s atmosphere, but prevent most of the outgoing heat from the surface and lower atmosphere from escaping into outer space.

Recycle: The reprocessing of used materials that would otherwise become waste by breaking them down and remaking them into new products.

Reuse: Putting an item to another use after its original purpose has been fulfilled; reusing an item for the same purpose over and over, such as refilling a water bottle, or for a new purpose such as using empty grocery bags as garbage can liners.

Keywords: global warming, greenhouse effect, recycle, reuse, engineering design, pollution, climate, trash, landfill


Before the Activity

  • Place a large container in the class for students to start filling  a couple weeks before with items they ordinarily would have thrown away or recycled. Ensure that cans are rinsed and no food items go into the materials box. Collect all other items to be used for the activity.
  • Lead the class in a discussion of the importance of reducing pollution due to global climate changes., and how recycling efforts can help (See associated Global Climate Change lesson.)
  • Optional: Make copies of the Carbon Footprint Worksheet, one per student. Divide the class into groups of 2-4 students. Have the members of each group begin to estimate their families’ carbon footprint and compare their results. This worksheet may be completed more fully as homework.

With the Students

1. Give the groups the joint project challenge to build a product with the following criteria:

• Use only materials listed in the materials list. These should be all reused materials, with a limited amount of bonding materials.

• The product must be useful — that is, not be an artistic sculpture, decoration, etc.

• A minimum of three items from the trash pile must be used to create the product.

2. Direct the students to begin by brainstorming ideas and producing an engineering drawing of their group design. Give them a limited amount of time –around 15 minutes — to complete this step. During the design session, have the students engage in open discussion of  ideas for their product. Remind them that in brainstorming, no idea or suggestion is “silly.” All ideas should be respectfully heard. Take an uncritical position, encourage wild ideas and discourage criticism of ideas. Ask them to write down all ideas and then agree on a design together.

3. After their drawing is reviewed by the teacher, they can start construction.

4. Once everyone is ready, each group should prepare a class presentation to explain how the product will be used. Group members should attempt to share  the speaking roles evenly, with one student  announcing the name of the product, another describing its use, others providing concluding comments or demonstration, etc.


Pre-Activity Assessment

Discussion: Solicit, integrate, and summarize student responses. How does recycling and reusing help our environment? Why do you think people do not recycle more often? Possible answers are given in the Table 1. Ask student how active their particular town or city is in recycling and  how to encourage greater participation in such efforts.

Table 1

Post-Activity Assessment

Concept Reflections / Journal Writing: Have the students reflect on the waste that they create on a daily basis. Ask them:

  • How much waste do you think you create each day?
  • What kinds of things do you throw away?
  • Which of these could be recycled instead of thrown away?
  • How could you change your habits to reuse more materials?

Activity Extensions

Discuss other ways  items we discard could be reused. Examples: old snowboard used for benches, an old can used for a pencil holder, etc. Then, ask students to draw something they could utilize at home that was made out of used materials. Have them label the picture with the materials they would need to build it. Ask each student to present their designs to the class.

Activity Scaling

  • For lower grades, this can easily be scaled down with more bonding materials to ease in construction.
  • For upper grades, give the students more difficult requirements, such as building a chair that can hold a certain amount of weight, etc.


State of Connecticut, Department of Environmental Protection, “Climate Change and Waste,” June 10, 2009, accessed June 22, 2009.

Colorado State University, Center for Science, Mathematics and Technology Education (CSMATE), CLTW West, Center For Learning & Teaching In The West (CLTW), Colorado Science & Mathematics Professional Development Web Site, “Your ‘Footprint’ on the Global Environment – The Greenhouse Effect,” accessed June 22, 2009.

Contributors: Christie Chatterley, Marissa Forbes, Malinda Schaefer Zarske, Janet Yowell, Karen King, Denise W. Carlson. © 2009 by by Regents of the University of Colorado

One Response to “Lesson: Life After Trash”

  1. wonderful site, wonderful activities….thank you!!

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