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Science lesson plan · 3rd grade (Year 4 in England) · 45 minutes

Planning a fair test

Working scientifically

CCSS NGSS.SEP 3CCSS NGSS.3-PS2-1England: KS2 Y3–Y4 Working scientifically

Objective and success criteria

Students will: Planning a fair test.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Choosing a measuring tool

Leads to: Independent, dependent and control variables

Materials: Simple equipment for a fair test, Results table template, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 5 min

  • 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 width of a leaf? (a stopwatch or timer / a thermometer / a ruler or tape measure / a measuring jug or cylinder) → 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 stopwatch or timer? (how much rainwater was collected / how tall a sunflower has grown / how long an ice cube takes to melt / how much juice is in a carton) → how long an ice cube takes to meltPrompt: What does this tool measure: length, temperature, mass, time or volume?
  3. Kofi wants to find out which ball bounces highest. Which tool helps most? (a measuring jug / a metre stick (long ruler) / weighing scales / a thermometer) → a metre stick (long ruler)Prompt: Bounce height is a length.

Hook · 5 min

  • 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.

I do: model it · 10 min

  • 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.

We do: guided practice · 10 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. Why is it a good idea to repeat a test several times? (Because the first try never counts / To check the results are reliable / To make the test unfair / To change the answer) → To check the results are reliablePrompt: What if one result was a mistake?
  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.

You do: independent practice · 10 min

  • 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.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Which question can be answered with a fair test? (Is a rainbow beautiful? / Does a heavier parachute fall faster? / What is your favourite plant? / Who is the best scientist?) → Does a heavier parachute fall faster?Prompt: A fair test changes one thing and measures another.
  2. Why is it a good idea to repeat a test several times? (To make the test unfair / To check the results are reliable / To change the answer / Because the first try never counts) → To check the results are reliablePrompt: What if one result was a mistake?

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Choosing a measuring tool.
  • Use concrete materials: simple equipment for a fair test.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Independent, dependent and control variables.
  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

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

Free lesson plan from eurekami.com/lesson-plan-builder

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Planning a fair test

Name

Date

Score/ 8

  1. Question 1

    Fair tests: which statement is true?

    • A. If a result surprises you, you should hide it.
    • B. One try is always enough.
    • C. In a fair test you change only one thing.
    • D. A fair test means everyone gets a turn.

  2. Question 2

    Ben tests whether salt water or tap water freezes faster. Which must he keep the same?

    • A. whether the water has salt
    • B. the type of water
    • C. the time each one takes to freeze
    • D. the volume of water in each cup

  3. Question 3

    Leo tests which paper towel soaks up the most water. What should he change?

    • A. the time he waits
    • B. the amount of water
    • C. the type of paper towel
    • D. the size of the towel

  4. Question 4

    Which question can be answered with a fair test?

    • A. Does a heavier parachute fall faster?
    • B. Who is the best scientist?
    • C. Is a rainbow beautiful?
    • D. What is your favourite plant?

  5. Question 5

    Omar tests how the length of a guitar string changes its note. He uses strings of different lengths. What else should stay the same?

    • A. the length of the strings
    • B. nothing else matters
    • C. how tight and thick the strings are
    • D. the note he hears

  6. Question 6

    Isla tests which ball bounces highest. She drops one ball from 1 m and another from 2 m. What is wrong?

    • A. She should not measure the bounce
    • B. Nothing, it is fair
    • C. The drop height should be the same
    • D. She should use only one ball

  7. Question 7

    Priya tests which surface a toy car rolls furthest on. What must she keep the same?

    • A. the height of the ramp
    • B. the type of surface
    • C. how far the car rolls
    • D. nothing

  8. Question 8

    Aisha measures how fast sugar dissolves in water at different temperatures. What does she measure?

    • A. the colour of the sugar
    • B. the temperature of the water
    • C. the time for the sugar to dissolve
    • D. the type of cup

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Answer key: Planning a fair test

  1. 1. C. In a fair test you change only one thing.

  2. 2. D. the volume of water in each cup

  3. 3. C. the type of paper towel

  4. 4. A. Does a heavier parachute fall faster?

  5. 5. C. how tight and thick the strings are

  6. 6. C. The drop height should be the same

  7. 7. A. the height of the ramp

  8. 8. C. the time for the sugar to dissolve