Food Chains & Energy Transfer

Activities to try

1. 1

   Build-and-test chain bench with a removal shock

   Why it works: A food chain is a flow of energy originating from the sun; breaking one link ripples up and down the chain, and predator/prey are roles in a relationship rather than fixed identities.

   1. Assemble a four-organism chain from pieces plus arrows, e.g. grass → rabbit → fox, extending to a fourth organism; draw the arrows in the direction energy travels (toward the eater).
   2. Tap or label each organism with its role — producer, prey, or predator — and justify each label aloud or in writing.
   3. Trace energy from a glowing sun source: show the sun's energy entering at the plant (producer) and pulsing along the arrows to each consumer; state in words where each animal's energy ultimately came from.
   4. Run a removal test: pull the rabbit out of grass → rabbit → fox and predict first, then observe the model — in this single-chain model the fox loses its food supply and the grass, no longer grazed by rabbits, tends to increase (real foxes might switch to other prey).
   5. Use a role toggle to show the same rabbit tagged as prey (to the fox) AND consumer (of grass); explain why both tags are correct at once.
2. 2

   Two-direction removal reasoning: the frog's two jobs

   Why it works: In this single chain, removing an organism tends to move the level below it UP (its predator is gone) and the level above it DOWN (its prey is gone); direction depends on which side of the removed organism you are on.

   1. Study the chain lettuce → slug → frog → heron.
   2. Predict: if a disease killed all the frogs, what happens to the number of slugs, and separately to the number of herons? Give a reason for each.
   3. Explain that the frog is BOTH predator (it eats slugs) and prey (herons eat it), and use that to justify why slugs go UP while herons go DOWN.
   4. Follow a second-order effect: once slugs increase, what then happens to the lettuce?
   5. Trace where the heron's energy originally came from — follow the chain back to the lettuce capturing sunlight — confirming the energy was inherited, ultimately from the sun.
3. 3

   Labelled chain reference and ecologist prediction talk

   Why it works: Roles and energy source can be read off a chain, and predictions must be justified by the chain's structure; feeding-relationship labels and energy-role labels are different kinds of label.

   1. Explore a labelled chain where each organism reveals its role and 'where its energy came from', with a sun element revealing the ultimate source — use this as a reference to check your own labels.
   2. With an ecologist prompt ('what if we removed the foxes?'), predict the knock-on effects and justify each prediction by pointing to the chain.
   3. Define producer, predator and prey in your own words, giving an example of each; distinguish predator/prey (a feeding relationship) from producer/consumer (an energy role).