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Teachers

Greenhouse Gases Exposed

Students perform a controlled experiment, then record and analyze their data. The lesson deepens understanding of the relationship between greenhouse gases and global warming.

Summary
Objectives
Materials Needed
Procedures
Assessment
Extension Activities
Relevant Curriculum Standards

SUMMARY:

Students will learn about the relationship of greenhouse gases and global warming through hands-on activities.

Estimated class time:
One class period.

OBJECTIVES:

Students will:

  • Define global warming and greenhouse effect.
  • Understand that carbon dioxide is a gas that creates a greenhouse effect and contributes to global warming.
  • Perform a controlled experiment, record and analyze data.

MATERIALS NEEDED:

Per Group

  • Goose-necked lamp or sunlamp to act as heat source
  • Newspaper
  • Three thermometers (at least one small enough to fit under an inverted beaker)
  • Two beakers, 500 ml or larger
  • 1000 ml Erlenmeyer flask
  • 50 ml vinegar
  • 3 g baking soda
  • Stopwatch or clock
  • Lab instruction sheets
  • Graph paper (optional)

For teacher demonstration:

  • Test tube
  • Candle
  • Small amount of baking soda
  • Small amount of vinegar

Internet Access

PROCEDURES:

Introduction:

  1. Ask students if they've ever been inside a greenhouse. Have them describe the temperature difference between outside the greenhouse and inside the greenhouse. Explain that the earth's atmosphere contains gases that produce that same greenhouse effect for the earth and that the class will be performing a lab activity to demonstrate that effect.
  2. Demonstration: Light a candle and set it on the demo table. Put a small amount of baking soda in a test tube. Pour enough vinegar in the tube to cover the baking soda. Have students observe the bubbles and explain that carbon dioxide gas is being produced by the reaction. Carbon dioxide is heavier than air. Prove this to the students by tilting the test tube over the candle, pouring the carbon dioxide onto the flame, extinguishing it. Explain that the students will be creating carbon dioxide in their lab groups, even if they can't see the gas.
  3. Divide the class into groups of 3 to 4 and provide each group with a copy of the lab instructions and the materials required. You may choose to pre-measure the baking soda and vinegar or allow students to measure out their own quantities using a balance and graduated cylinders.
  4. Provide graph paper and assistance, if necessary, to graph data.
  5. Provide each student (or group) with a Global Warming worksheet, which directs students through some of the information from the Environmental Change and Our Health site, to work on between taking temperature readings.
  6. As a class, discuss what was learned from this activity being sure that students understand the distinction between the physical barrier of an actual greenhouse and the heat-trapping effect of certain atmospheric gases.

Greenhouse Gases Exposed! Lab Instructions

  1. Place a layer of newspaper on your lab table. (This will minimize any effect of the table on the temperatures.)
  2. Measure 3 grams of baking soda and add to 1000 ml Erlenmeyer flask.
  3. Pour 50 ml of vinegar into the flask.
  4. Let reaction continue until the bubbling has stopped.
  5. Set up a lamp on your lab table.
  6. Place one thermometer directly on the newspaper. This will be the control.
  7. Place a small thermometer under a beaker that is turned upside down on the table.
  8. Pour the gas of the flask into a second beaker, being careful not to pour out the liquid. Place a thermometer in the beaker, and set it on the newspaper right side up.
  9. Arrange the two beakers and the thermometer under the lamp, all three at an equal distance from the lamp. Turn the lamp on.
  10. Record the temperatures of each thermometer in the data table without disturbing the thermometers.
  11. Continue taking temperature readings every two minutes for 30 minutes, or until there has been no change in temperature for 4 consecutive readings.
  12. Graph results and answer the discussion questions.

Data Table

Time

Temperature of control

Temperature under beaker

Temperature in carbon dioxide

0 min.

 

 

 

2 min.

 

 

 

DISCUSSION:

  1. Why was it necessary to have a thermometer sitting out by itself?
  2. What did the upside-down beaker represent?
  3. Why did the beaker with carbon dioxide in it have to be left right side up?
  4. Which situation resulted in a higher temperature-the control thermometer or the upside down beaker?
  5. Which situation resulted in a higher temperature-the control thermometer or the beaker with carbon dioxide?
  6. How did the temperature of the upside down beaker compare to the temperature of the beaker with carbon dioxide?
  7. Can an invisible gas have the same effect as a greenhouse? Explain your answer.

Go to "Taking Our Temperature". Read the introduction, and then click on "What is global warming?" Answer the following.

  1. What was significant about the 1990's decade?
  2. How much has the global surface temperature increased in the last century?
  3. Why is that increase a concern to scientists?
  4. What is global warming?
  5. What are fossil fuels?
  6. What are greenhouse gases?
  7. Where do greenhouse gases come from?
  8. Is the greenhouse effect necessarily a bad thing for the earth?
  9. How does the greenhouse effect lead to global warming?
  10. Explore some of the other links of the website. List five different possible consequences of global warming.

ASSESSMENT:

  • Lab participation
  • Lab worksheets
  • Global Warming worksheet
  • Discussion participation

EXTENSION ACTIVITIES:

  • Research the U.S. government's position on global warming.
  • Find news and journal articles related to global warming. Summarize and share with the class.
  • Explore the interactive activity, "Your Carbon Diet" at www.pbs.org/wgbh/warming/carbon/ from the NOVA/Frontline site "What's up with the weather?"
  • Explore the interactive map of fossil fuel facts at www.pbs.org/frontlineworld/stories/colombia/oila.html on Frontline's "World" site.

RELEVANT CURRICULUM STANDARDS:

Content Standard A:
As a result of activities in grades 5-8, all students should develop abilities necessary to do scientific inquiry:

Students should develop general abilities, such as systematic observation, making accurate measurements, and identifying and controlling variables.

Content Standard B:
As a result of their activities in grades 5-8, all students should develop an understanding of transfer of energy:

The sun is a major source of energy for changes on the earth's surface. The sun loses energy by emitting light. A tiny fraction of that light reaches the earth, transferring energy from the sun to the earth.

Heat moves in predictable ways, flowing from warmer objects to cooler ones, until both reach the same temperature

Content Standard F:
As a result of activities in grades 5-8, all students should develop understanding of natural hazards:

Human activities also can induce hazards through resource acquisition, urban growth, land-use decisions, and waste disposal. Such activities can accelerate many natural changes. Human activities also can induce hazards through resource acquisition, urban growth, land-use decisions, and waste disposal. Such activities can accelerate many natural changes.

 

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