Today is rung 4 of 6 on this topic
Ecosystems, food webs and energy flow
Can do: Traces energy from the sun through a food web and predicts the effect of removing one species.
Why it matters
It's systems thinking — the understanding that changing one thing changes several others, which transfers far beyond biology.
What it looks like when it's wobbly
Thinks of food chains as straight lines with no consequences, and can't reason about knock-on effects.
⏱️ Two-minute check
"If all the foxes disappeared, what happens to the rabbits, and then to the grass?"
Solid looks like: A two-step chain of consequences, not just the first one.
The full activity for this topic · 25 minutes
Web of String
- 1Write local plants and animals on cards and lay them out.
- 2Connect each with string wherever one eats the other. It becomes a web, not a chain.
- 3Cut one string — remove a species — and trace which connections fail.
- 4Ask what happens to the numbers of everything else, two steps out.
- 5Find a real example: wolves in Yellowstone, or a local invasive species.
If it's too hard
A five-species chain rather than a full web.
If it's too easy
Add decomposers and nutrient cycling, and explain why the web needs them.
Say this
"That's what happens next. And then what? Keep going two more steps."