• 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 turn into fish / They would increase / They would stay exactly the same / They would decrease) → They would increasePrompt: What eats tadpoles?
2. Bees are declining. Why could this affect fruit farmers? (Bees eat fruit / Bees make the rain / Fewer flowers would be pollinated, so less fruit forms / Fruit trees need honey to grow) → Fewer flowers would be pollinated, so less fruit formsPrompt: What do bees carry between flowers?
3. Food webs: which statement is NOT true? (Plants do not compete with each other. / Plants compete for light, water and minerals. / Animals often compete for food, water and space. / Predator and prey populations often rise and fall in cycles.) → Plants do not compete with each other.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: 10, 3, 9, 2, 9. What is the mean number of daisies per quadrat? → 6.6Prompt: Add up all the counts.
2. The mean number of buttercups in a 0.25 m² quadrat is 2. The field is 500 m². Estimate the number of buttercups in the field. → 4000Prompt: 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. The mean number of buttercups in a 0.25 m² quadrat is 13. The field is 200 m². Estimate the number of buttercups in the field. → 10400Prompt: How many quadrats would fit in the field?
2. How can you see how plant species change from a hedge to the middle of a field? (Sample at night / Count only the tallest plants / Place one quadrat by the hedge only / Place quadrats at regular intervals along a transect line) → Place quadrats at regular intervals along a transect linePrompt: A transect is a line across a habitat.

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