Paddles, Packed Meals, and Energy Models

Lunch at the Canoe Portage

A canoe-camping group stops at a portage, a place where campers carry boats between waterways. Before carrying their canoes, the campers eat a packed lunch of cooked rice, peas, and cooked chicken. An adult prepared and safely packed the meal before the trip. The group wants to predict how these foods can help them paddle and carry equipment later. They make models to trace the energy in their lunch.

The campers read notes about where their foods came from. Rice grains grew on rice plants. Peas are seeds that grew on pea plants. Both kinds of plants used light from the sun to make food. Some of that food was stored in the grains and seeds. The chicken ate rice grains before the trip. Chickens eat other foods too, but the campers choose to follow the rice route in their model. The chicken's body used energy from its food as it grew and moved.

Food contains stored energy. Animals, including people, can use energy from food to move, grow, repair their bodies, and keep warm. Eating a plant part and eating another animal give energy different routes to follow. A model can help the group keep track of those routes. It does not need to show the farm, the food container, or every step of preparing lunch. Those details matter for other questions, but the campers are studying where food energy came from.

The group agrees on an arrow key: an arrow points from an energy source toward the receiver. An arrow from the sun to a plant represents light energy reaching the plant. An arrow from a plant to an animal represents energy transferred when the animal eats plant food. An arrow from one animal to another represents energy transferred through eating. The campers' models do not show exact energy amounts. They also do not show how long a meal will support paddling. To answer those questions, the group would need more information.