Everything for the Ecosystems test: study cards, the traps to dodge, and a practice quiz at three levels — Foundation, On-Level, and Challenge. Work here, or print it and use a pencil — both count.
Energy flows one way and leaves as heat at every step — about 90% of it. Matter cycles and comes back; energy does not. That is why there are always fewer foxes than rabbits.
Four things people get wrong
⚠️People often think…
Energy gets recycled through the ecosystem.
Matter cycles. Energy does not. It enters from the sun, moves up one way, and leaves as heat at every step — which is why the sun has to keep shining.
Matter goes in circles. Energy goes in one door and out as heat.
⚠️People often think…
The top predator gets the most energy.
It gets the least. Only about 10% passes up at each step, so a top predator is living on what is left after two or three of those cuts.
Higher up the chain, less energy — and fewer animals.
⚠️People often think…
Decomposers are the optional part of a food web.
They are the part that returns the matter. Without them, nutrients stay locked inside dead bodies and the producers eventually run out.
No decomposers, no way back to the soil.
⚠️People often think…
Plants get their food from the soil.
Plants MAKE their food by photosynthesis, out of light, air and water. Soil supplies water and minerals — useful, but not food.
Soil is the water bowl, not the plate.
Follow the ten percent
1Watch one
1,000 units of energy are in the grass. How much reaches the fox, two steps up?
Each step passes about 10%.
Grass 1,000 → rabbit 100.
Rabbit 100 → fox 10.
About 10 units. The other 990 left as heat.
2Do one with me
10,000 units are in the plants. Follow them two steps up.
After the first step:
After the second step:
The energy that did not pass up left as
💬One sentence, then you move on
Why are there always fewer foxes than rabbits?
3Try one
Where does a plant's food come from? Write your answer.
I want a hint first
Soil gives water and minerals. Food is something the plant builds for itself.
💬Last one — then you're done here
Why would an ecosystem stop working without decomposers?
Where this goes
Where this lives
A compost pile turning scraps back into soil, and the reason a pound of beef takes far more land than a pound of beans.
What this feeds
Next unit is populations and communities — what happens when the food at one level runs short.
Name one thing you ate today and say how many steps it was from the sun.
One card at a time — tap “Show me” to check yourself, then Next. Start at Foundation; when those feel easy, climb.
Helpful Hints
🔑 The one rule that unlocks the whole topic
Energy FLOWS one way; matter CYCLES around. Energy enters as sunlight, moves up the food chain, and leaves as heat — gone. Matter (carbon, water, nitrogen) is reused forever.
Energy flows. Matter loops.
🏹 Food chain arrows
The arrow points in the direction the ENERGY moves — from the eaten to the eater. Grass → rabbit → fox means the rabbit gets energy FROM grass.
The arrow means “feeds into,” not “attacks.”
⚠️ Traps the test loves
Energy is NOT recycled — only matter cycles. Energy escapes as heat at every step.
The top predator gets the LEAST energy — only ~10% passes up each level.
Decomposers are not optional — without them, nutrients stay locked in dead bodies.
Plants don’t get food from soil — they MAKE it by photosynthesis; soil gives water and minerals.
👥 Know your roles
Producers (plants, algae): make food from sunlight — energy’s entry point.
Decomposers (bacteria, fungi): break down dead matter, returning nutrients to soil — the recyclers.
🎯 How the test will ask
Expect a food web: “what happens if the ___ disappears?” Trace every arrow touching it, both directions.
10% rule math: 10,000 units in grass → 1,000 in rabbits → 100 in foxes. Practice dividing by 10.
Cycle questions want the loop named step by step — where the carbon/water goes, in order.
✅ Before the test, can you…
Sort ten things into biotic and abiotic?
Draw a food chain with correct arrows?
Apply the 10% rule to a 3-level pyramid?
Explain why energy must keep entering but matter never runs out?
Walk the water cycle and the carbon cycle out loud?
Term
Meaning in 10 words or less
Ecosystem
All living things + nonliving surroundings in an area.
Biotic factor
A living (or once-living) part of an ecosystem.
Abiotic factor
A nonliving part — sun, water, soil, temperature.
Population
All members of ONE species in one area.
Community
All the populations living together in an area.
Producer
Makes its own food; energy’s entry point.
Consumer
Gets energy by eating other organisms.
Decomposer
Breaks down dead matter; recycles nutrients.
Food web
All the food chains connected together.
Energy pyramid
Shows energy shrinking ~90% at each level.
Evaporation
Liquid water becoming water vapor.
Condensation
Vapor becoming liquid — clouds form.
Precipitation
Rain, snow, sleet — water falling back down.
Nitrogen cycle
Nitrogen looping air → soil → living things → back.
Pick your level
Look back at anything you missed — the hint that appeared is exactly what to reread tonight.
How sure did you feel?
Workshop
Work like an ecologist: sort the living from the non-living, label the energy pyramid, walk one water molecule around its cycle, then explain why a food chain cannot have ten links.
Your practice never leaves this device. There is no account and no sign-in. Your work is saved in this browser only, and you can erase it whenever you want.
Your practice record — saved on this device
This is your record of the module on screen — it stays here and goes nowhere. Independent means you got it right on the first tap; supported means you got it after the explain-and-retry, or marked ‘I had it’ on a revealed answer. Both count, and neither is a grade. If your teacher asks, copy the row or show them this screen.
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The answer key is for a teacher: it prints only from here, for the unit on screen. Print the study packet prints the study pages and a blank quiz — never the answers.