• 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 the mass of a pumpkin? (a measuring jug or cylinder / weighing scales / a stopwatch or timer / a ruler or tape measure) → weighing scalesPrompt: 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? (the mass of a bag of flour / how heavy an apple is / how long a toy car takes to roll down a ramp / how long a worm is) → how long a worm isPrompt: What does this tool measure: length, temperature, mass, time or volume?
3. Which tool would show that the water in a bowl is getting colder? (a magnifying glass / a measuring jug / a thermometer / a ruler) → a thermometerPrompt: Colder means the temperature is going down.

• 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. Isla tests which ball bounces highest. She drops one ball from 1 m and another from 2 m. What is wrong? (She should not measure the bounce / The drop height should be the same / She should use only one ball / Nothing, it is fair) → The drop height should be the samePrompt: What is she trying to compare?
2. Which question can be answered with a fair test? (What is your favourite plant? / Who is the best scientist? / Is a rainbow beautiful? / Does a heavier parachute fall faster?) → Does a heavier parachute fall faster?Prompt: A fair test changes one thing and measures another.

• 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. Priya tests which surface a toy car rolls furthest on. What must she keep the same? (the type of surface / the height of the ramp / nothing / how far the car rolls) → the height of the rampPrompt: Only the surface should change.
2. Fair tests: which statement is true? (One try is always enough. / You should change as many things as possible. / If a result surprises you, you should hide it. / Repeating a test helps you check your results.) → 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.