Lesson: Gumdrop Ozone Depletion Model: Battling for Oxygen

Quick Look

Grade Level: 6 (4-6)

Time Required: 45 minutes

Lesson Dependency: None

Subject Areas: Chemistry, Earth and Space, Physical Science, Science and Technology


Using gumdrops and toothpicks, students conduct a large-group, interactive ozone depletion model. Students explore the dynamic and competing upper atmospheric roles of the protective ozone layer, the sun's UV radiation and harmful human-made CFCs (chlorofluorocarbons).
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

A mother applying sunscreen on her child to protect her from the sun.
Sunscreen is applied to protect against harmful UV radiation
Copyright © CDC http://www.cdc.gov/cancer/skin/images/mother_child_sun_protection.jpg

Engineering Connection

Many engineers invent new technologies and/or re-designed old technologies to entirely avoid producing harmful CFCs, which deplete the Earth's protective ozone layer. These changes to design, manufacturing processes, regulations and practices have reduced the US CFC emissions dramatically. Some changes included new types of refrigerator coolants and the elimination of many aerosol spray propellants. The modern engineer always keeps long-term sustainability in mind as a design objective.

Learning Objectives

A partial globe image showing the North American and European continents, with concentric colored areas over the U.S. and Europe, and especially red over the eastern U.S. and western Europe.
Figure 1. Chlorofluorocarbon (CFC) concentrations in U.S. and Europe. Red indicates highest concentrations.
Copyright © Joseph Spahr, UCLA, Insights Magazine, at: http://ct.gsfc.nasa.gov/insights/vol17/chemistry.html

After this activity, students should be able to:

  • Understand and explain the different processes that destroy ozone in the Earth's atmosphere.
  • Create an interactive model of ozone destruction.
  • Compare a model of ozone with what it represents.
  • Develop an understanding of the global trend towards ozone depletion and recovery.
  • Collect data and create a graph of global ozone amounts over the last 50 years.

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.

NGSS Performance Expectation

MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. (Grades 6 - 8)

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This lesson focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Analyze and interpret data to determine similarities and differences in findings.

Alignment agreement:

Science knowledge is based upon logical and conceptual connections between evidence and explanations.

Alignment agreement:

Develop a model to predict and/or describe phenomena.

Alignment agreement:

Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.

Alignment agreement:

Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

Alignment agreement:

Models can be used to represent systems and their interactions.

Alignment agreement:

  • Students will develop an understanding of the relationships among technologies and the connections between technology and other fields of study. (Grades K - 12) More Details

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  • Visual displays are used to interpret data. (Grade 5) More Details

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  • Display numerical data in plots on a number line, including dot plots, histograms, and box plots. (Grade 6) More Details

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  • Fluently divide multi-digit numbers using standard algorithms. (Grade 6) More Details

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  • Use the particle model of matter to illustrate characteristics of different substances (Grade 6) More Details

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Worksheets and Attachments

Visit [www.teachengineering.org/lessons/view/cub_air_lesson08_activity1] to print or download.

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Have you ever been sun burnt? How does this happen? Were you in the sun too long? Ultraviolet rays from the sun cause damage to our skin, as seen by sun burns and sun tans. Ozone is one barrier to letting those ultraviolet (UV) rays reach us on Earth.

When an ozone molecule absorbs UV light from the sun, it breaks down into an oxygen (O2) molecule and an oxygen atom (O). Sometimes the oxygen molecule breaks into two oxygen atoms as well. Normally, the free oxygen atom combines with other oxygen atoms or molecules to produce ozone again. Under normal circumstances, ozone is continuously being destroyed and regenerated by the sun's ultraviolet rays. When there are no outside disturbances, this process of breaking down ozone and building it back up occurs at a constant rate that keeps us protected from a lot the sun's harmful UV rays. However, harmful pollutants (such as CFCs from aerosol cans) can also break down ozone by converting it into oxygen molecules and atoms. When this happens ozone breaks down much faster than it can build up and "holes" appear in the ozone layer. These holes are not actual holes, but areas where the ozone layer is so thin that it lets more UV rays through. The air currents that carry the pollution determine where the holes in the ozone exist.

Scientists and engineers have been measuring the ozone layer for many years, and encouraging people to stop the destruction of the ozone layer by reducing the human-created pollutants that contribute to its depletion. The most common ozone-destroying pollutants are in a class of chemical compounds called chlorofluorocarbons (CFCs), which have been used in air conditioner coolants and aerosol spray propellants. Today, many nations and industries have taken steps, including the design of new technologies by engineers, to reduce the production of CFCs and protect the ozone layer from harmful CFCs.

As pollution to the atmosphere increases, the amount of ozone decreases. In other words, an increase in the amount of pollutants that reach the upper atmosphere disrupts the process that makes ozone our safe protective shield. In today's activity, we are going to model just how pollutants destroy ozone.


Pre-Activity Assessment

Discussion: Ask the students and discuss as a class:

  • Have you ever been sun burnt? How does this happen? Were you in the sun too long? (Discussion points: Ultraviolet rays from the sun cause sun burns and sun tans on our skin. The ozone layer is one barrier to letting those ultraviolet rays reach us on Earth.)

Activity Embedded Assessment

Drawing the Data: Use the butcher paper to make a striking visual representation of the data. Have the students cut a 2 ft. by 2 ft. square for each run of the exercise. Have them draw the O2 and O3 molecules of a given (consistent) size distributed evenly over the paper. They should only draw as many molecules on the paper as were left at the end of the respective run (that is, approximately 100 molecules pre-1965, approximately 0-10? molecules in 1988). (Time-saving tip: Some students could be working on these drawings while the other students are conducting the activity. For example, after the first few runs, a few students could start drawing the first picture while the other students continue with subsequent runs. Students can trade responsibilities so everyone gets a chance to build or destroy molecules.) Place the drawings in chronological order so students can see the effect over time of CFCs on the number of O2 and O3 molecules in the atmosphere.

Post-Activity Assessment

Worksheet: Have the students complete the Battling for Oxygen Worksheet, which includes questions about the activity and interpreting a graph.

Question/Answer: Ask the students the questions at the end of the Procedure section, and discuss as a class.

Lesson Extension Activities

Have students diagram how CFCs break the bonds in oxygen atoms.

Have students diagram what happens when the sun's rays enter an ozone layer with and without a hole, as well as the effects this has on the Earth's surface.

Have students research what other global-wide steps have been taken to reduce the emissions of CFCs into the atmosphere since the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. (For example, a 1990 update to the Montreal Protocol was signed by 70+ nations, and a 1992 Copenhagen meeting resulted in an agreement by many nations.) What changes are being made? Is it working? (By 1992, global CFC production was one half of the 1988 production, the historic high, and down to the 1972 level.) Are you using any CFC products in your daily life or home? How are governments, scientists and engineers involved?


Chlorinated Fluorcarbons (CFCs), Man-Made Chemicals, Global Change Course. Global Learning Resource Network, Iowa State University. Accessed July 24, 2004. http://www.meteor.iastate.edu/gccourse/chem/ozone/chlorinated.html

Global CFC Production. Updated 1998. Chapter Two: The State of the Environment – Global Issues Figure, GEO-2000, Global Environment Outlook, United Nations Environment Programme (UNEP). Accessed November 9, 2004. (Good graph of global CFC production, 1986-1996, comparing contributions from industrialized countries and developing countries.) http://www.unep.org/geo2000/english/i26a.htm

Global CFC (chlorofluorocarbon) Production, Environment Canada. Updated 2002. United Nations Environment Programme Ozone Secretariat, Kenya. Accessed November 9, 2004. (CFC production data 1950 to 1997; Excel file to download.) http://www.ec.gc.ca/

Ozone Depletion (archive of links for various articles on this topic). Updated June 15, 2004. FAQs.org. Accessed July 24, 2004. http://isc.faqs.org/faqs/ozone-depletion/

Rekacewicz, Philippe. Global CFC Production. Updated March 17, 2003. UNEP (United Nations Environment Programme) GRID-Arendal, Norway. Accessed November 9, 2004. (Good graph of global CFC production, 1950-1992, with the Montreal Protocol marked.) http://sedac.ciesin.columbia.edu/ozone/

SEDAC: Stratospheric Ozone and Human Health Project. Columbia University, New York City. Accessed July 24, 2004. http://sedac.ciesin.columbia.edu/ozone/

Stattersfield, Eloise. High Level Ozone. University of Bristol, UK. Accessed July 24, 2004. (Very good summary information.) http://www.chm.bris.ac.uk/motm/ozone/high.htm

Stratospheric Ozone Information for Children. Updated September 20, 2002. Kidzone, The Green Lane, Environment Canada. Accessed December 21, 2011. http://www.ec.gc.ca/ozone/


© 2004 by Regents of the University of Colorado.


Amy Kolenbrander; Tom Rutkowski; Janet Yowell; Natalie Mach; Tyman Stephens; Malinda Schaefer Zarske; Denise Carlson

Supporting Program

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


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: October 25, 2019


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