Lesson: Let's Heat Things Up!

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

A diagram shows some of the energy coming from the sun reflected by the atmosphere and some of it absorbed by the atmosphere and the Earth. It also shows how some energy from the Earth gets trapped in the atmosphere.
Figure 1. The greenhouse effect.
copyright
Copyright © Project A.I.R.E., EPA, www.epa.gov/

Summary

Students observe demonstrations, and build and evaluate simple models to understand the greenhouse effect, the role of increased greenhouse gas concentration in global warming, and the implications of global warming theory for engineers, themselves and the Earth. In an associated literacy activity, students learn how a bill becomes law and research global warming legislation.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Humans' excess production of "greenhouse gases" is creating an environment unfit for healthful living. In response to this global warming, engineers of all disciplines are examining how these greenhouse gases are formed, so they can work to reduce their production. Some engineers re-design vehicles and factories to reduce the emissions that cause greenhouse gases. Others are working to change manufacturing processes, regulations and practices, in an effort to clean up many chemical sources.

Learning Objectives

After this lesson, students should be able to:

  • Understand that human activities can create an increase in carbon dioxide concentrations (air pollution).
  • Explain the global warming theory.
  • Understand that carbon dioxide gas is a greenhouse gas whose increased concentration in the atmosphere is contributing to global warming.
  • Describe how global warming may impact an engineer's decisions, their own lives and the Earth.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Ask questions to clarify evidence of the factors that have caused the rise in global temperatures over the past century. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Display numerical data in plots on a number line, including dot plots, histograms, and box plots. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Decisions to develop and use technologies often put environmental and economic concerns in direct competition with one another. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Interpret and analyze data about changes in environmental conditions – such as climate change – and populations that support a claim describing why a specific population might be increasing or decreasing (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Introduction/Motivation

Ask students to do a "splash sheet" about the greenhouse effect and global warming. (A "splash sheet" is similar to a brainstorm, but includes pictures, diagrams, words, etc., to help students quickly jot down their ideas.) Consider assigning this as homework the night before the lesson.

Share the ideas from the splash sheets as a class.

Many scientists believe that the Earth is getting warmer. They think this is happening because of an increased greenhouse effect. What is the greenhouse effect? Maybe you have already felt a miniature version of the greenhouse effect. Has this happened to you? It's a hot summer day and your parents have parked the car in the sun and no one opened the windows. How does it feel inside the car? It is very hot because the sun's energy is trapped inside the car. When you feel that trapped energy as heat, you have just felt the greenhouse effect. This is why no one should be left in a car on a warm, sunny day (including pets), because the inside temperature of the car can become over 100ºF, even with the windows slightly opened! The sun warms our planet. We feel the sun's energy as heat, but more of this heat is getting trapped near Earth by greenhouse gases like carbon dioxide.

Some people think the levels of carbon dioxide in our atmosphere are too high. But, what are we supposed to do... stop breathing?! They predict that the Earth's temperature will rise, making it unhealthy for life. The World Resources Institute says electric utility companies, industry, businesses, homes and transportation cause carbon dioxide levels to build up in our atmosphere.

From where does carbon dioxide come? (As necessary, review the carbon cycle with the students; see The Carbon Cycle Diagram attachment.) Why is it considered such a problem? What does it have to do with the greenhouse effect and global warming?

Lesson Background and Concepts for Teachers

The Earth's climate has changed many times in the past. Subtropical forests have spread from the south to more temperate (milder, cooler climates) areas. Millions of years later, ice sheets spread from the north covering much of the U.S., Europe and Asia with glaciers. Our climate appears to be changing again, but scientists think that humans are causing most of it. (Did earlier life cause other climate changes somehow?)

The Greenhouse Effect

The greenhouse effect is a naturally occurring phenomenon in which the atmosphere of the Earth traps heat from the sun (see The Greenhouse Effect Diagram attachment). Typically, our atmosphere absorbs just the right amount of heat so that living things can survive, and reflects back into the atmosphere the rest of the heat. Essentially, the atmosphere acts like the glass in a greenhouse. As a result of this, the Earth's surface is about 53°F (12°C) warmer than it would be without the greenhouse effect.

However, some gases (especially CO2, methane, nitrous oxide, and CFCs) also contribute to trapping heat within the atmosphere. Methane is a product of natural decay from living (or once-living) things; nitrogen oxides are generally a result of human-made burning, automobiles and similar internal-combustion engines; and CFCs are a class of chemicals once commonly used in air conditioners, refrigerators and as the pressurizing gas in aerosol spray cans. The higher the concentration of these gases in the atmosphere, the warmer the Earth's temperature becomes. CO2 makes up about 50% of the heat-retaining gases in the atmosphere, and methane makes up about 20%. Each molecule of methane absorbs infrared radiation 20 times more effectively than a molecule of CO2.

A pie chart illustrates the composition of the Earth's atmosphere today: 78% nitrogen, 21% oxygen, 9% argon, 0.03% carbon dioxide and 0.07% other gasses. A second pie chart illustrates the early Earth atmosphere composition: 80% nitrogen, 18% oxygen, 1% hydrogen and 1% water vapor.
Figure 2. Composition of the Earth's atmosphere, today and in earlier times.
copyright
Copyright © Natalie Mach, Graduate Fellow, Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder, 2003.

Global Warming Theory

Global warming is a scientific theory that says that increased amounts of greenhouse gases (such as carbon dioxide) in the atmosphere trap too much heat and cause the average temperature on Earth to increase. Scientists advise that even a 2-3ºF increase in the average temperature of the Earth could trigger disasters. Some scientists predict that if the amount of CO2 in the air doubles, the average world temperature would rise about 4.5%.

The amount of CO2 entering the air increases when fossil fuels are burned and the excess cannot be used by plants (especially since we are eliminating them, too). The excess CO2 absorbs heat energy from the sun, keeping the heat near the surface of the Earth, which raises the Earth's temperature. The concentration of CO2 in the atmosphere has doubled in the last 100 years and scientists expect it to double in the next 100 years as well.

Scientists predict that these changes will trigger disaster. For example, a major shift in weather patterns could cause droughts, tropical storms and increase temperatures that would make some currently habitable areas of the Earth become uninhabitable. It is also speculated that melting polar ice caps could cause a rise in sea levels and, in turn, flood low-lying areas, such as coastal cities like New York City and San Francisco. The melting of the icecaps could also dilute marine saline concentrations, threatening marine life.

While most scientists believe that the greenhouse effect will gradually warm the Earth's climate, some have a different view. Some scientists predict that as the temperature rises, more water will evaporate from the oceans, resulting in so many clouds that it could block out sunlight, causing an overall decrease in the Earth's average temperature. This increased atmospheric reflectivity is also called an increase in the Earth's albedo.

Photosynthesis

Forests have been called the "lungs of the Earth" because animals inhale oxygen and exhale carbon dioxide in the process of breathing, and plants take in carbon dioxide and give off oxygen in the process of photosynthesis. See The Carbon Cycle Diagram attachment.

Every year, more than 28 million acres of tropical forest are cut and burned to clear land for farming. Many scientists agree that about 25% of the CO2 being released into the air comes from burning the rain forests. For example, it is estimated that in 1989 alone, the burning of Brazilian forests probably added about 350 million tons of CO2 to our atmosphere.

Engineering

Environmental engineers are concerned about photosynthesis because plants help clean the air of harmful CO2 gas, replacing it with oxygen. With the decreasing numbers of trees in the world, the air is not being cleaned as well. Additionally, the CO2 levels continue to increase due to increasing numbers of automobiles and industrial pollution. Environmental engineers are continually challenged to find methods to reduce CO2 emissions from industry and cars, and find ways to clean our polluted air.

Vocabulary/Definitions

albedo: The reflectivity of a substance, usually a percentage of the amount of incoming radiation that is reflected.

global warming: A scientific theory that says that increased amounts of greenhouse gases (such as carbon dioxide) in the atmosphere trap too much heat and cause the average temperature on Earth to increase.

Greenhouse effect: A naturally occurring phenomenon in which the atmosphere of the Earth traps heat from the sun.

habitable: Suitable to live in or on.

photosynthesis: The process by which plants take in carbon dioxide and give off oxygen.

Associated Activities

  • Hot Stuff! - Students observe demonstrations, and build and evaluate simple models to understand the greenhouse effect and the role of increased greenhouse gas concentration in global warming.
  • It's Really Heating Up in Here! - Students create and observe a greenhouse effect model and discuss the implications of global warming theory for engineers, themselves and the Earth.
  • Pollution Politics - In this literacy activity, students learn how a bill becomes law in the U.S. Congress, and research legislation related to global warming.

Lesson Closure

Ask students to create a final, more detailed and thoughtful splash sheet describing their full understanding of the greenhouse effect and global warming. Consider using butcher block paper or large, bulletin board-size paper for the splash sheets. Display these in the classroom or the school common area.

Have the students create a pie chart or bar graph using the data on the Sources of CO2 Emissions attachment (see the Assessment section for details).

Attachments

Assessment

Pre-Lesson Assessment

Splash Sheet: Ask students to create a "splash sheet" about the greenhouse effect and global warming. A splash sheet is similar to a brainstorm, but includes pictures, diagrams, words, etc., to help students quickly jot down their ideas. Consider assigning this as homework the night before the lesson. If done in class, provide students with large sheets of butcher block paper on which to create their splash sheet.

Post-Introduction Assessment

Question/Answer: From where does carbon dioxide come? (As necessary, review The Carbon Cycle Diagram with the students.) Why is it considered such a problem? What does it have to do with the greenhouse effect and global warming?

Lesson Summary Assessment

Graphing: According to the Energy Information Administration, the sources of CO2 emissions in the U.S. in 2000 were: 40.5% from electricity generation, 33% from transportation, 16.5% from industrial, 6% from residential and 4% from commercial. Using this data, have students make a pie chart and/or a bar graph. Ask them to include a paragraph explaining what the graph represents and how this information relates to the greenhouse effect and global warming. Refer to the Sources of CO2 Emissions attachment.

Create a Poem: Have the students write a short poem that expresses what they understand about global warming and how it may affect our environment in the next 50 years.

Lesson Extension Activities

Explore carbon monoxide production in more detail. Will our individual efforts really make a difference or do we need to address CO2 production at another level? Are there other greenhouse gases to which we should be paying more attention?

Have students act out the greenhouse effect. Some students can be a CO2 wall, some can be the Earth, and others can be the trapped energy between the greenhouse gasses and the Earth.

References

Blashfield, Jean F. and Black, Wallace B. Recycling. Chicago, IL: Children's Press Inc., 1991.

Energy Information Administration. Department of Energy. www.eia.gov. Accessed August 17, 2004. (For great information and energy statistics)

Environmental Issues. Teacher Created Materials, 1994. Online at Teacher Created Resources. www.teachercreated.com.

The EPA Global Warming Kids Page. Updated July 12, 2004. U.S. Environmental Protection Agency. www.epa.gov. Accessed August 17, 2004.

Goodman, Billy. A Kid's Guide to How to Save the Planet. New York, NY: Avon Books, 1990.

Investigations in Science – Ecology. Huntington Beach, CA: Creative Teaching Press, 1995.

Rain Forest – Extended Thematic Unit. Teacher Created Materials, 1995. Online at Teacher Created Resources. http://www.buyteachercreated.com/estore/product/0674

Science Plus – Technology and Society (Level Green). Holt, Rinehart and Winston Inc., 1997.

Williams, Jack. Understanding Greenhouse Gases. Written November 7, 2000. Updated July 23, 2003. USA Today. www.usatoday.com/weather/climate/wco2.htm. Accessed August 17, 2004.

Contributors

Amy Kolenbrander; Janet Yowell; Natalie Mach; Malinda Schaefer Zarske; Denise Carlson

Copyright

© 2004 by Regents of the University of Colorado.

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: July 20, 2017

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