However, we often act as though life on Earth were a massive tool box, with many unnecessary minor nuts and bolts. In North America we once used the wonder pesticide DDT, but were ignorant of its effect on the rest of the food chain, where it caused egg shell thinning in predatory birds and tainted mothers' milk. Today, third world countries use DDT widely. We condone the liquidation of ancient forests around the world by doing little to stop it. We don't know the answers to these questions - perhaps we can't know them, until it's too late.
Sunlight is converted into chemical energy by green plants.
Part of that energy is captured by herbivorous insects and vertebrates when they eat the plant. Carnivores then eat herbivores. In reality, however, the flow of energy through an ecosystem is more like a web. Species share energy back and forth in subtle ways. Each member of your class will play one or more parts in a Craters food web.