Objectives:

• Students will understand how the automobile contributes to altering atmospheric concentrations of greenhouse gases.
• Students will propose strategies to limit automobile emissions.

Subjects: Math, Science, Social Studies

Level: Grades 6-8, adaptable for higher levels

Time: 2 50-minute class periods for Part A;  Part B can be a homework assignment.

Materials: 10 automobiles, adult to supervise, watch, sock, tape, permanent marker, safety goggles, paper mask, metric ruler, materials to measure CO2 emissions (there are several ways to do this, CLICK HERE for information).

Procedure: Depending on the level of students and what you want them to gain from the activity, several variations are possible.  Can be done as a class science project.

Part A

1. Have students summarize the discussion from the introductory activity.
2. Focus the discussion on the automobile as a source and have students hypothesize which automobiles they feel are the biggest culprits.  Have them state a reason for their hypothesis.  Record different hypotheses.
3. Ask the students to discuss how they could test their hypotheses.
4. Divide the class into 10 groups.  Have each group reach a consensus about which hypothesis they would like to test.
5. Have students record the hypothesis on their lab paper and give an explanation as to why this is what they think will happen.
6. Select 10 automobiles from your school parking lot that cover a wide spectrum - old, new, large, small, economy, luxury.  Get staff permission (and keys) to use cars in experiment.
7. Each group will be assigned a car to test.  First have them test for CO2 emissions.  The students that will be collecting the sample should wear safety goggles and a mask to cover their nose and mouth.  The sample should be taken 30 centimeters directly in front of the tailpipe. Have students stand to the side of the tailpipe to collect the sample.   Have one student start the car and run it for 30 seconds while the sample is collected.  Then turn the car off.  As detailed above there are several ways to test for CO2. Choose the method that fits the materials you have on hand.  The sooner the sample can be tested the better.
8. Give each group a sock of the same type.  Have them place the sock tightly over the mouth of the car's exhaust.  Have them start the engine of the car and run it for 3 minutes.  Turn the car off.
9. Remove the sock and return to class.
10. Turn the sock inside out so particulates are visible and label it with the year and model of the car tested.
11. Arrange socks in order from dirtiest to cleanest based on student observation.  Compare the results to the hypotheses.
12. If your state has automobile emissions tests, have students bring in the test results to compare.  The sock fabric will only trap the large pollutant particles.  Smaller particles, such as CO2, will pass through the cloth.
13. Have students answer the follow-up questions on their lab report.  Discuss answers.

Discussion Questions: See Student Page.

Part B

1. Have students track how far the car travels in one week using the odometer.  Have them compute the amount of CO2 produced in pounds/kilograms using the following information:
   
   1. 1 mile = 1.609km, 1 gallon = 3.785 liters, 1 pound = 0.435kg
   2. Approximate miles per gallon of the vehicle they tested
   3. Approximately 20lbs (9 kg) of CO2 are produced per gallon of gasoline consumed. 2.  Have students write a response to the following:  If global warming is a reality, human beings will need to make many changes in order to adapt to a warmer climate.  What steps do you think should be taken now to try to reduce the impact of global warming in the future?

Click here for References and Web Sites specific to this lab.