• 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 the small fish died, what would happen to the herons? (They would increase / Nothing / They would decrease or move away / They would eat algae) → They would decrease or move awayPrompt: What do herons eat in this web?
2. Why is a food web more realistic than a single food chain? (Food webs have no producers / Food webs only show plants / Animals only ever eat one food / Most animals eat, and are eaten by, more than one kind of living thing) → 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? (Predator and prey populations often rise and fall in cycles. / Removing one species can affect many others in a food web. / Removing a predator always helps every other species. / Plants compete for light, water and minerals.) → 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: Sampling with quadrats. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Five 1 m² quadrats contained these numbers of daisies: 7, 4, 11, 4, 10. What is the mean number of daisies per quadrat?
• Step 1: (7 + 4 + 11 + 4 + 10) ÷ 5 = 7.2
• Step 2: So the answer is: 7.2
• Answer: 7.2
• 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. Five 1 m² quadrats contained these numbers of daisies: 5, 6, 6, 10, 2. What is the mean number of daisies per quadrat? → 5.8Prompt: Add up all the counts.
2. The mean number of buttercups in a 0.25 m² quadrat is 12. The field is 100 m². Estimate the number of buttercups in the field. → 4800Prompt: How many quadrats would fit in the field?

• 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. Why should quadrats be placed at random? (Because it is quicker / So the results are always the same / To find the most plants / To avoid bias, so the sample represents the whole area) → To avoid bias, so the sample represents the whole areaPrompt: What if you only put quadrats where flowers look thickest?
2. The mean number of buttercups in a 1 m² quadrat is 15. The field is 500 m². Estimate the number of buttercups in the field. → 7500Prompt: How many quadrats would fit in the field?

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