• 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. Mateo wants to know if plants grow better with more light. Which plan is fair? (Same light for every plant / Same plant type, same water, different amounts of light / Different plants, different water, different light / More water for the plant in the light) → Same plant type, same water, different amounts of lightPrompt: Only the thing being tested should change.
2. Omar tests how the length of a guitar string changes its note. He uses strings of different lengths. What else should stay the same? (how tight and thick the strings are / nothing else matters / the length of the strings / the note he hears) → how tight and thick the strings arePrompt: Tightness and thickness also change the note.
3. Fair tests: which statement is true? (Repeating a test helps you check your results. / If a result surprises you, you should hide it. / 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 temperature of water affect how quickly sugar dissolves? Which is the independent variable (the one you change)? (water temperature / time for the sugar to dissolve / amount of light / mass of sugar) → water temperaturePrompt: Independent variable: the one you change. Dependent variable: the one you measure.
2. Investigation: How does exercise affect heart rate? Which is the dependent variable (the one you measure)? (minutes of exercise / height of the cress / the same person / heart rate (beats per minute)) → heart rate (beats per minute)Prompt: 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 size of a parachute affect how long it takes to fall? Which is the independent variable (the one you change)? (size of the parachute / drop height / mass of the bob / time to fall) → size of the parachutePrompt: 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 a control variable (one you keep the same)? (heart rate (beats per minute) / length of wire / brightness of the bulb / number of cells) → length of wirePrompt: 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.