The students will drop CO₂ molecules off at trees (often represented by Poly Spots); each tree can absorb 4 CO₂ molecules. The game is timed, so that students will observe how many CO₂ molecules produced by their activities could be absorbed by the trees. Then, Suzanne resets the game based on the forests and activities of today. Here, many trees have been chopped down, so there are fewer Poly Spots where students can deposit their CO₂ molecules, and daily activities yield much higher emissions. For example, there are now cars and buses that the students will use as transport methods, which will require them to carry many more CO₂ molecules as they proceed to different stations.
Students notice that it is much harder to make sure all the CO₂ molecules are absorbed, and many more molecules remain in the atmosphere. After the timer ends, the class discusses the effects of having so much more CO₂ in the atmosphere and reflects on the ways in which different activities yielded different emissions levels (i.e., driving a car emits much more CO₂ than riding a bike or walking). Part of this discussion involves addressing the fact that many technological advances that have made our lives much easier have had detrimental effects on our environment.
Finally, Suzanne and her students discuss practical ways in which students can ameliorate the imbalance of CO₂ production and absorption. Suzanne states that she makes sure the actions she suggests are realistic to what third through fifth graders can accomplish, such as taking better care of trees in their backyards or schools (as opposed to saying that they will plant more trees, or stop cutting them down). She also suggests actions such as buying lunch from school when you forget your lunch from home, as having someone drive your lunch to you at school releases another set of emissions.
