• 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 increase / They would decrease / They would turn into fish) → They would increasePrompt: What eats tadpoles?
2. Rabbits and sheep both eat grass in the same field. This is an example of… (photosynthesis / predation / competition / decomposition) → competitionPrompt: They both want the same limited resource.
3. Food webs: which statement is NOT true? (Animals often compete for food, water and space. / Plants compete for light, water and minerals. / Removing one species can affect many others in a food web. / Removing a predator always helps every other species.) → 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: 3, 11, 12, 3, 9. What is the mean number of daisies per quadrat? → 7.6Prompt: Add up all the counts.
2. The mean number of buttercups in a 1 m² quadrat is 10. The field is 100 m². Estimate the number of buttercups in the field. → 1000Prompt: 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. Five 1 m² quadrats contained these numbers of daisies: 4, 3, 11, 12, 10. What is the mean number of daisies per quadrat? → 8Prompt: Add up all the counts.
2. Why should quadrats be placed at random? (To find the most plants / Because it is quicker / To avoid bias, so the sample represents the whole area / So the results are always the same) → To avoid bias, so the sample represents the whole areaPrompt: What if you only put quadrats where flowers look thickest?

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