• 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. Pond food web: algae are eaten by tadpoles and water fleas. Tadpoles and water fleas are eaten by small fish. Small fish are eaten by herons. If all the small fish died, what would probably happen to the tadpoles at first? (They would stay exactly the same / They would turn into fish / They would decrease / They would increase) → They would increasePrompt: What eats tadpoles?
2. Why is a food web more realistic than a single food chain? (Most animals eat, and are eaten by, more than one kind of living thing / Food webs only show plants / Animals only ever eat one food / Food webs have no producers) → Most animals eat, and are eaten by, more than one kind of living thingPrompt: Does a fox eat only rabbits?
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. / 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: 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 breeding pairs of a bird species in 2010 and 320 in 2024. What was the percentage decrease? → 20 %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. Biodiversity: which statement is NOT true? (Fertiliser running into lakes can cause algae to grow and oxygen to fall. / 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.) → Human activity has no effect on extinction rates.Prompt: What does biodiversity actually measure?
2. A survey found 300 hectares of rainforest in 2010 and 240 in 2024. What was the percentage decrease? → 20 %Prompt: Find the decrease first.

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