• 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 become rabbits / They stop eating seeds / They increase, because foxes stop eating / Their numbers fall, because foxes eat more mice) → Their numbers fall, because foxes eat more micePrompt: Foxes still need to eat.
2. What does "interdependence" mean in an ecosystem? (Only predators matter / Living things depend on each other, so a change to one affects others / Every animal lives alone / Plants do not need animals at all) → 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? (Animals often compete for food, water and space. / Removing one species can affect many others in a food web. / Plants compete for light, water and minerals. / A food web contains only one food chain.) → A food web contains only one food chain.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: Biodiversity under pressure and how we protect it. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A survey found 200 breeding pairs of a bird species in 2010 and 180 in 2024. What was the percentage decrease?
• Step 1: 200 − 180 = 20
• Step 2: 20 ÷ 200 × 100 = 10
• Step 3: So the answer is: 10 %
• Answer: 10 %
• 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. A survey found 400 hectares of rainforest in 2010 and 360 in 2024. What was the percentage decrease? → 10 %Prompt: Find the decrease first.
2. Draining peat bogs to sell peat as garden compost harms the climate. Why? (Decaying or burned peat releases stored carbon as carbon dioxide / It creates acid rain / It makes the ozone layer thicker / Peat absorbs too much oxygen) → Decaying or burned peat releases stored carbon as carbon dioxidePrompt: Peat is partly decayed plant material.

• 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 8 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 survey found 200 breeding pairs of a bird species in 2010 and 180 in 2024. What was the percentage decrease? → 10 %Prompt: Find the decrease first.
2. Biodiversity: which statement is NOT true? (Fertiliser running into lakes can cause algae to grow and oxygen to fall. / Breeding programmes can help protect endangered species. / Deforestation reduces biodiversity and adds carbon dioxide to the air. / Human activity has no effect on extinction rates.) → Human activity has no effect on extinction rates.Prompt: What does biodiversity actually measure?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-10.