• Quick retrieval from earlier learning (Planning a fair test). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Why is it a good idea to repeat a test several times? (To change the answer / To check the results are reliable / Because the first try never counts / To make the test unfair) → To check the results are reliablePrompt: What if one result was a mistake?
2. Ben tests whether salt water or tap water freezes faster. Which must he keep the same? (the type of water / the time each one takes to freeze / whether the water has salt / the volume of water in each cup) → the volume of water in each cupPrompt: He is changing the type of water and measuring the time.
3. Fair tests: which statement is true? (If a result surprises you, you should hide it. / Repeating a test helps you check your results. / A fair test means everyone gets a turn. / One try is always enough.) → Repeating a test helps you check your results.Prompt: Think about what makes a test fair.

• Show a simple experiment with one thing changed and ask what makes it a fair test.
• Share the objective: Independent, dependent and control variables. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Investigation: Does the surface area of a puddle affect how fast it evaporates? Which is the independent variable (the one you change)?
• Step 1: Change: surface area of the water. Measure: time for the water to evaporate. Keep the same: volume of water, temperature of the room.
• Step 2: So the answer is: surface area of the water
• Answer: surface area of the water
• 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. Investigation: Does the size of a parachute affect how long it takes to fall? Which is the independent variable (the one you change)? (size of the parachute / mass hanging from it / surface area of the water / time to fall) → size of the parachutePrompt: Independent variable: the one you change. Dependent variable: the one you measure.
2. Investigation: How does the amount of light affect the growth of cress? Which is the dependent variable (the one you measure)? (height of the cress / amount of light / distance the car travels / amount of water) → height of the cressPrompt: Independent variable: the one you change. Dependent variable: the one you measure.

• 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. Investigation: Does the surface area of a puddle affect how fast it evaporates? Which is a control variable (one you keep the same)? (heart rate (beats per minute) / time for the water to evaporate / surface area of the water / volume of water) → volume of waterPrompt: Independent variable: the one you change. Dependent variable: the one you measure.
2. Investigation: Does the number of cells (batteries) affect how bright a bulb is? Which is the dependent variable (the one you measure)? (length of wire / brightness of the bulb / time for the water to evaporate / number of cells) → brightness of the bulbPrompt: Independent variable: the one you change. Dependent variable: the one you measure.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-5.