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

1. Which tool would you use to measure how far a paper plane flew? (a measuring jug or cylinder / weighing scales / a stopwatch or timer / a ruler or tape measure) → a ruler or tape measurePrompt: Is it a length, a temperature, a mass, a time or an amount of liquid?
2. What could you measure with a ruler or tape measure? (how long a candle burns / how long a toy car takes to roll down a ramp / how far a paper plane flew / the mass of a bag of flour) → how far a paper plane flewPrompt: What does this tool measure: length, temperature, mass, time or volume?
3. Zara wants to know if her bean plant grows taller each day. What should she use? (weighing scales / a ruler / a stopwatch / a thermometer) → a rulerPrompt: She wants to know how tall it is.

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

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Leo tests which paper towel soaks up the most water. What should he change?
• Step 1: He is testing types of paper towel, so that is the only thing he changes.
• Step 2: So the answer is: the type of paper towel
• Answer: the type of paper towel
• 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. Mateo wants to know if plants grow better with more light. Which plan is fair? (Same light for every plant / More water for the plant in the light / Same plant type, same water, different amounts of light / Different plants, different water, different light) → Same plant type, same water, different amounts of lightPrompt: Only the thing being tested should change.
2. Aisha measures how fast sugar dissolves in water at different temperatures. What does she measure? (the time for the sugar to dissolve / the type of cup / the colour of the sugar / the temperature of the water) → the time for the sugar to dissolvePrompt: She changes the temperature. What does she then look at?

• 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. Omar tests how the length of a guitar string changes its note. He uses strings of different lengths. What else should stay the same? (the length of the strings / how tight and thick the strings are / nothing else matters / the note he hears) → how tight and thick the strings arePrompt: Tightness and thickness also change the note.
2. Fair tests: which statement is true? (One try is always enough. / A fair test means everyone gets a turn. / Repeating a test helps you check your results. / You should change as many things as possible.) → Repeating a test helps you check your results.Prompt: Think about what makes a test fair.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-3.