Sunlight Paths at the Reuse Depot

The Cardboard Stack and the Loading-Court Strip

The Riverbend Reuse Depot sorts cardboard, metal, and glass for reuse. A narrow strip of sunflowers grows beside the loading court. Finches eat seeds from the sunflower heads. On some days, sparrows eat caterpillars from the sunflower leaves. The class wanted to model where the food energy in these animals began.

During the first observation period, the strip received about 6 hours of direct sunlight each day. Then workers stacked a tall group of flattened cardboard boxes beside the strip to keep them dry before baling. The stack blocked afternoon sunlight, so the strip received about 3 hours of direct sunlight each day. Workers kept the watering schedule the same. The class recorded what happened before and after the stack was placed.

A science note helped the class make its model: plants use light energy to make food. An animal gets food energy by eating a plant or by eating another animal that ate a plant. The arrows in the model show the direction in which food energy is transferred. A Sun label shows where the light energy in the plant's food began.

The class did not measure the amount of energy in each seed or the amount of food energy used by each bird. Its records can support a pathway model, but they cannot tell how far a bird will fly or how much energy a bird receives from one meal.