Most students have heard the term “going green.” This is because there is a worldwide movement that encourages people to live a more sustainable lifestyle. Many of us now hand over reusable shopping bags when cashiers ask us “paper or plastic?” In some cities, there are carpooling traffic lanes. We have environmentally friendly clothing. We even have cars that are considered environmentally conscious.

How does “going green” relate to the classroom? The National Science Education Standards state that students should have an understanding of human impact on the environment.

However, how often do students think about their impact in their own daily surroundings? Have students ever analyzed the impact of their television watching? What about the impact their refrigerator has on the environment? Or the washer that cleans their clothes?

Often teachers introduce “going green” by having students analyze their carbon footprint on Internet sites. Calculate Your Footprint  and Zerofootprint are two sites often used by teachers in middle school classrooms.

Where do you go once kids have calculated their carbon footprint? Connecting these activities with current science news is a great teaching opportunity. As a class, read “Is Green Insurance Worth the Price?“  from the Bucks Blog in the New York Times, March 11, 2010.

Part of this article discusses rebuilding an energy-efficient home. Discuss with students the various ways to make their own homes energy efficient. List student ideas on the board. When students are done offering suggestions, revisit the idea of energy-efficient household appliances (if students didn’t suggest this idea, ask them what they think about it). Then engage students in learning about appliances with this lesson.

Objective:

The purpose of this lesson is to introduce the students to the idea of decreasing one’s energy consumption by changing to more energy-efficient appliances. However, with every decision there are consequences. Though there will be less energy cost each year, the cost of buying the new appliance may not be balanced out for a number of years. The students must weigh the costs and benefits of choosing to be more energy efficient through the use of systems of equations.

The students will use the provided data to create cost over time equations. They will compare three different graphs representing the three possible models for each appliance. 

The students are also invited to come up with their own ideas on how to become more energy efficient and cut costs.

Introduction:

Explain to students that you are trying to save money and be more environmentally friendly at the same time. Tell them that you need their help to decide what you should do to become energy efficient.

Activity:

Give students a copy of this worksheet to work on as a group. Make collaborative learning groups before class. Be sure to mix groups with various mathematical abilities. Each group should have a “stronger” math student. The data they will need is located on this worksheet. The worksheet has students analyze the energy consumption of four appliances that they use on a daily basis. Students will figure out how many kilowatts/year each appliance uses and then use this information to estimate the annual cost/year for each appliance. The worksheet also provides information on two additional appliances that are more energy efficient. Students will use this information to come up with cost equations that the class will analyze graphically. This analysis should help students to determine which option is the most “green” and cost friendly.

After completion of this worksheet students will be able to:

-analyze their energy usage at home

-analyze data in order to select energy efficient appliances

- work with multiple equations to determine the financial benefits for changing to more energy efficient appliances.

Closure:

After groups have finished coming up with their cost equations, graph the equations on the board/overhead. Then, as a class, discuss the graphs and what they mean. Some questions to ask include:

1) What are some possible choices for decreasing my bills in the long run?

2) How many years into the future does it make sense for me to replace all of my appliances? How do you know?

3) What are other examples of ways to decrease one’s energy bill? Are these better ideas than replacing your appliances? Why?

4) Why do we care about our use of resources, especially energy?

5) Should individuals with energy-efficient homes have reduced insurance costs?

Extension:

Students can think about their own home. Have students come up with five ways they could decrease their home energy bill each year. Have students draw up a proposal and present it to their parents.