• Quick retrieval from earlier learning (Food webs and interdependence). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Woodland food web: grass is eaten by rabbits and mice. Seeds are eaten by mice. Rabbits are eaten by foxes. Mice are eaten by foxes and owls. If disease killed most rabbits, what might happen to the mice? (They increase, because foxes stop eating / They stop eating seeds / Their numbers fall, because foxes eat more mice / They become rabbits) → Their numbers fall, because foxes eat more micePrompt: Foxes still need to eat.
2. What does "interdependence" mean in an ecosystem? (Living things depend on each other, so a change to one affects others / Only predators matter / Plants do not need animals at all / Every animal lives alone) → Living things depend on each other, so a change to one affects othersPrompt: Think of bees and flowers.
3. Food webs: which statement is NOT true? (Predator and prey populations often rise and fall in cycles. / Plants compete for light, water and minerals. / Removing a predator always helps every other species. / Animals often compete for food, water and space.) → Removing a predator always helps every other species.Prompt: Think about what happens when one population changes.

• Show a food web and ask what would happen if one animal disappeared.
• Share the objective: Energy transfer and pyramids. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Producers in a field capture 20000 kJ of energy. About 10% of the energy passes to each next level. How much energy reaches the tertiary consumers, in kJ?
• Step 1: 20000 ÷ 1000 = 20
• Step 2: So the answer is: 20 kJ
• Answer: 20 kJ
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. Producers in a field capture 10000 kJ of energy. About 10% of the energy passes to each next level. How much energy reaches the secondary consumers, in kJ? → 100 kJPrompt: 10% means divide by 10 at each step.
2. A level of a food chain contains 2000 kJ. The next level gets 200 kJ. What is the percentage efficiency of the energy transfer? → 10 %Prompt: efficiency = energy passed on ÷ energy available × 100

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. A pyramid of biomass shows… (the number of species in the world / the height of the animals / the temperature at each level / the mass of living material at each level) → the mass of living material at each levelPrompt: "Bio" means life, "mass" means…
2. Producers in a field capture 100000 kJ of energy. About 10% of the energy passes to each next level. How much energy reaches the secondary consumers, in kJ? → 1000 kJPrompt: 10% means divide by 10 at each step.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.