• 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 stop eating seeds / They become rabbits / 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? (Removing one species can affect many others in a food web. / Plants compete for light, water and minerals. / Predator and prey populations often rise and fall in cycles. / 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 240 breeding pairs of a bird species in 2010 and 192 in 2024. What was the percentage decrease? → 20 %Prompt: Find the decrease first.
2. Why is high biodiversity good for an ecosystem? (It makes the ecosystem more stable because species depend on many others / It stops the water cycle / It means fewer species compete / It removes all predators) → It makes the ecosystem more stable because species depend on many othersPrompt: Think about what happens if one food source disappears.

• 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 survey found 240 breeding pairs of a bird species in 2010 and 192 in 2024. What was the percentage decrease? → 20 %Prompt: Find the decrease first.
2. Biodiversity: which statement is NOT true? (Breeding programmes can help protect endangered species. / Human activity has no effect on extinction rates. / Deforestation reduces biodiversity and adds carbon dioxide to the air. / Global warming is changing where some species can live.) → 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.