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        Understanding Air: Air Pollution and Modeling Pollutants with LEGO® Bricks

        In this lesson, students learn about the chemical reactions that release various pollutants into the atmosphere and what happens when pollutants in the air are exposed to sunlight. They model incomplete combustion using LEGO bricks, and explore the connection between air quality and environmental health.

        Lesson Summary


        Note: A related lesson explains the composition of air and demonstrates how combustion releases carbon dioxide (CO2) into the atmosphere, the relationship between CO2 levels and global temperatures, and the health implications of increasing CO2 levels. If you want to provide students with foundational content and an introduction to using LEGO bricks to build molecules, do this lesson first: Understanding Air: Climate Change and Modeling Combustion with LEGO® Bricks Lesson Plan.

        Air pollution is a public health threat. Emissions from car and truck tailpipes, factories, power plants, and other sources can compromise our respiratory and cardiovascular systems, resulting in some very serious health effects: asthma, bronchitis, emphysema, chest pain, and lung cancer. EPA monitors and reports on five major air pollutants found throughout the United States: ground-level ozone, particle pollution (or particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. These pollutants can harm your health and the environment.

        In this lesson, students discover how air pollutants are added into the atmosphere, how they react chemically in the presence of sunlight, and the effects they have, specifically on human health. The lesson begins with a brief review of combustion and an explanation of incomplete combustion. Students use LEGO bricks to demonstrate what happens when a fuel does not combust completely, and the further chemical reactions that occur when pollutants in the air are exposed to sunlight. Next, students learn about some of the negative health effects associated with certain common air pollutants. They watch a video about a community experiencing a number of health problems, including asthma and birth defects, which may stem from exposure to coal plant emissions. Students then learn about air quality and explore an interactive activity that explains the Air Quality Index (AQI)—a gauge of daily air quality developed by EPA—and highlights some of the health risks associated with various air pollutants. The lesson ends with a small-group activity that asks students to research and report on an air quality forecast in a city across the country.


        • Visualize air pollutant molecules
        • Discover what happens when hydrocarbons burn in the presence of too little oxygen
        • Model what happens to combustion byproducts in the presence of sunlight in the atmosphere
        • Explain the health effects of exposure to common air pollutants
        • Discuss ways to reduce both the production of and exposure to air pollutants

        Grade Level: 5–8

        Suggested Time

        • Two class periods (approx. 45 minutes for Parts I-II and 45 minutes for the remainder); additional time may be required to complete the activities proposed for advanced learners

        Media Resources


        Before the Lesson

        • If possible, arrange for students to work in pairs or in groups of three; each pair or group will share one set of LEGO bricks.
        • Make color printouts of the handouts for distribution to each pair or group. If you are unable to do this, arrange to show the sheets on an overhead projector.

        Printing instructions: Set scaling to "0%" or "none" so that the LEGO bricks on the printouts are actual size. Print two-page documents back-to-back and laminate, if possible; or print one-sided and use a plastic sleeve.

        The Lesson

        Part I: LEGO Building Activity—Incomplete Combustion

        1. In the first part of this lesson, students learned what happens when a hydrocarbon fuel—in this case, propane—combusts completely: it yields water and CO2 molecules. Now let’s learn what happens when combustion is incomplete.

        Incomplete combustion occurs when there is not enough oxygen present during the combustion reaction. While the hydrocarbons and oxygen (the reactants) may successfully reform as water and CO2 molecules (the products), there will be other reaction products formed as well.

        2. Explain to the class that they are now going to use their LEGO sets to demonstrate what happens when a fuel does not combust completely. Distribute one LEGO® Atoms and Molecules Layout Mat Document to each group of two or three students. This document explains the contents of the LEGO brick set. Explain (or remind them) that each brick represents an atom, and they will use these atoms to build molecules.

        Next, distribute the Burning Fuel: Incomplete Combustion Document. Using Side 1 as a guide, have students construct hydrocarbon and oxygen molecules with the LEGO bricks. Wait until all students have done this, and then instruct them to put back the extra bricks. Circulate and check.

        Note: Side 1 of the handout will provide shapes for C3H8 and O2. Side 2 shows the products that form once a reaction takes place.

        Here are the chemical reactions that are possible:

        Chemical Reactions Formulas

        Now have students turn over the handout and build the molecules on Side 2 using the same atoms.

        Emphasize that when modeling a combustion reaction, students should first build as many water molecules as they can, followed by CO2 molecules. Then the remaining atoms may be combined to make other molecules.

        3. Explain to the class that the substances that get pumped into the air from incomplete combustion—namely, soot (elemental carbon) and carbon monoxide (CO)—can impact both environmental and public health.

        Part II: LEGO Building Activity—Modeling Other Pollutants

        4. Next, introduce the idea that other pollutants in the air result from incomplete combustion of other fuels. For example, car and truck engines burn gasoline. Gasoline is a mixture of several different kinds of hydrocarbons including octane (so-called because each molecule has eight carbon atoms). Electricity-generating plants burn coal, another kind of hydrocarbon. Both gasoline engines and power plants release pollutants into the atmosphere. In the presence of sunlight, the pollutants can react further with other molecules in the air to form new pollutants as well.

        Ask students if they’ve heard of a form of air pollution called smog. Ask what they think it is made from. Explain that smog is a collection of pollutants, including nitrogen dioxide and soot, which results from incomplete combustion. Smog is a serious health hazard, especially in cities and surrounding areas.

        5. Distribute the Air Chemistry and Pollution Document. Tell students that they will now model some other common pollutants found in air—namely, sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3). Students will read the handout and create the pollutant stories by building the molecules and placing them in the outlined spaces on Side 1. They can then check their answers on Side 2.

        6. For advanced learners: Using the Air Chemistry and Pollution Reactions Document, students can model additional chemical reactions that occur when pollutants react with components of air, including oxygen and water, in the presence of sunlight. Among the new pollutants created when this happens are nitric oxide (NO), sulfurous acid (H2SO3), and sulfuric acid (H2SO4).

        Side 1 does not include instructions on how to do the reactions, but Side 2 contains the construction details for the molecules the students will need to use.

        Before moving to the next steps, have students put away the LEGO bricks and close the lid to avoid possible distractions. They can keep the handouts in front of them, as you may want to refer to the pollutants and storyboards found on them.

        7. Explain to students that they are going to explore in greater detail some of the health effects associated with the common air pollutants identified in the lesson. Show students the Teen Maps Contaminants from a Coal Plant Video. The video highlights some of the health effects that may be associated with exposure to pollutants coming from a coal-fired power plant in an urban community. (Note: The first minute of the video is most relevant to the lesson. You may want to stop screening the video after Marisol says "… a coal power plant, and they have to see it every day.")

        After watching the video, ask students to name two negative health effects associated with exposure to the pollutants mentioned in the video. Before moving on, briefly review the pathways pollutants may take from their sources into a person’s body.

        Part III: Air Quality and Your Health

        8. Introduce the concept of air quality. Explain to students that air quality reflects the condition of air relative to human health needs. For example, air quality is poor and deemed unhealthy if it contributes to illness or other health problems. To gauge air quality, tell students we can measure the levels of certain pollutants in the air.

        Have students do a small-group activity. The Air Quality Index Interactive provides information on why and how EPA monitors air quality, explains the values it uses to assess it, describes various air pollutants and their sources, and highlights some of the health risks associated with these pollutants. Assign each group one of the pollutants reported in the AQI (choose among ozone, carbon monoxide, and sulfur dioxide). Groups should be prepared to briefly report to the class the following:

        • Name of the pollutant
        • Chemical formula
        • Source(s)
        • Potential health risks of exposure to the pollutant

        After the presentations, discuss the following questions as a class:

        • Which parts or systems of the body seem to be most susceptible to the effects of poor air quality?
        • Which segments of a population are most at risk from exposure to air pollution?

        Part IV: Reducing Your Risks

        9. Explain to students that public health officials at the federal, state, and local levels are responsible for making and enforcing laws to protect people from the effects of air pollution. Tell students that individuals also can take action to reduce air pollution and protect their health from common pollutants.

        As a class, discuss how each of the following actions may help:

        • Car pooling, using public transportation, biking, or walking
        • Setting thermostats higher in the summer and lower in the winter, and using energy-efficient appliances and equipment in your home
        • Scheduling outdoor activities for morning or early evening hours

        The discussion should focus on reducing activities that generate air pollutants and reducing exposure to pollutants when they are generally at their highest levels.

        Check for Understanding

        In their groups, have students go to the Introduction page of the Air Quality Index Interactive and click on the Resources button. (You may also divide the class into five equal-sized groups.) Next, click on the “AIRNow” link. The AIRNow site, which was developed by EPA, NOAA, and other national, state, local, and tribal agencies, offers daily AQI forecasts as well as real-time AQI conditions for more than 300 cities across the U.S.

        Assign each group one of the “Highest 5” cities in today’s forecasts across the country. Each group will nominate one person to report to the class the following details relating to the city they’ve been assigned:

        • Name of the city and state
        • The AQI forecast (e.g., “moderate,” “unhealthy”) and the related health message
        • Which pollutants are at especially high levels
        • How this pollutant gets into the air

        Students may refer back to the Air Quality Index Interactive for supporting information as needed, or use resources provided on the site.


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