With the aid of your students, prepare a flowchart of the ways humans use energy to obtain their foods. Begin on the left side of the chalkboard with the sun, and on the right side of the board, write the word "you." Then, in between, add all the ways humans use energy to obtain their food in western society. It is not a simple relationship between sun-producers-consumers-humans because we use so many inputs of fossil fuels to grow our crops, prepare fertilizers, grow genetically specialized seeds, plant and harvest the crops, truck the crops to a storage facility and on to processing plants, use energy to process them, truck them to the grocery store, and use energy to light and warm the store, plus perhaps refrigerate the foodstuff. Then, you hop into your car, drive to the store, shop, drive home again, and put your food into your refrigerator. Producing beef, pork, chicken, or other meats takes even more energy, because the energy put into the crops has to be included, plus that used in animal husbandry, genetics, raising the livestock, getting them to market, butchering at the packing plant, then trucking the meat to the grocery store where it must be kept under refrigeration until it is purchased by you.
This ends up being an interesting exercise--plus we see how wasteful we can be! Discuss alternatives to using fossil fuels at so many different places within our food web.
Discuss also how subsistence farmers in the world use their crops and a scant amount of fossil fuel to feed themselves.
Never is the opportunity to marvel over the diversity of life on this planet as good as it is with this chapter. The majority of students have traveled to some extent, but rarely have they traveled widely, and certainly less likely with the purpose of examining ecosystems. Using 2 X 2 slides, a video, or filmstrip, share the features of a number of ecosystems with your students. Show them what a tropical rain forest looks like, or travel in your classroom to an arctic tundra. Discuss the unique adaptations of plants and animals that live in each place. Include information on what people are doing to save certain areas or how they have intruded into the ecosystems.