Students predict how a pond food web responds to change on this 5th grade science sheet. A diagram links algae, water plants, tadpoles, snails, insects, fish, frogs and a heron. Three scenarios, a frog disease, extra algae and a new fish-eating bird, each ask students to mark two organisms as increase, decrease or stay the same and to write a because line. Page 3 holds sample reasons. It supports NGSS 5-LS2-1.
5-LS2-1
“Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.”
Students follow the arrows from one organism to the next to predict how a change spreads through the pond.
A diagram of eight organisms with arrows from food to eater, then a table for a disease that reduces the frog population. Students predict what happens to insects and to the heron.
Extra sunlight lets the algae grow, and students predict tadpoles and snails. A flock of fish-eating birds arrives, and students predict fish, then tadpoles and snails together. Each row has a because line.
Every prediction with a sample reason, such as fewer frogs meaning more insects and less food for the heron.
Trace first
Ask students to trace the arrows with a finger before they predict. Scenario 3 needs two steps, fish down and then tadpoles and snails up.
The heron question
The heron also eats fish, so scenario 1 invites a short debate. Accept a decrease when the reason mentions less food.
Because sentences
Ask for a full sentence that uses eat or eaten by. A reason such as less food is too thin to show the link.
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