• 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. Leo tests which paper towel soaks up the most water. What should he change? (the amount of water / the size of the towel / the time he waits / the type of paper towel) → the type of paper towelPrompt: In a fair test you change only one thing: the thing you are testing.
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? (nothing else matters / the note he hears / how tight and thick the strings are / the length of the strings) → how tight and thick the strings arePrompt: Tightness and thickness also change the note.
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 number of cells (batteries) affect how bright a bulb is? Which is the independent variable (the one you change)? (type of bulb / surface area of the water / brightness of the bulb / number of cells) → number of cellsPrompt: Independent variable: the one you change. Dependent variable: the one you measure.
2. Investigation: How does the height of a ramp affect how far a toy car travels? Which is the dependent variable (the one you measure)? (the same car / distance the car travels / height of the ramp / brightness of the bulb) → distance the car travelsPrompt: 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: How does the mass of a pendulum bob affect the time of one swing? Which is a control variable (one you keep the same)? (time for the sugar to dissolve / mass of the bob / time for one swing / length of the string) → length of the stringPrompt: Independent variable: the one you change. Dependent variable: the one you measure.
2. Investigation: How does exercise affect heart rate? Which is the independent variable (the one you change)? (the same person / minutes of exercise / heart rate (beats per minute) / mass of the bob) → minutes of exercisePrompt: 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.