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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 how heavy a pet hamster is? (a measuring jug or cylinder / a ruler or tape measure / weighing scales / a stopwatch or timer) → 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? (how much milk is in a glass / how much rainwater was collected / how warm the classroom is / the width of a leaf) → the width of a leafPrompt: 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 thermometer / a measuring jug / a metre stick (long ruler) / weighing scales) → 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? (To make the test unfair / To change the answer / To check the results are reliable / Because the first try never counts) → To check the results are reliablePrompt: What if one result was a mistake?
  2. Which question can be answered with a fair test? (Is a rainbow beautiful? / Who is the best scientist? / Does a heavier parachute fall faster? / What is your favourite plant?) → Does a heavier parachute fall faster?Prompt: A fair test changes one thing and measures another.

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. 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 length of the strings / the note he hears / how tight and thick the strings are) → 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. / You should change as many things as possible. / A prediction says what you think will happen.) → A prediction says what you think will happen.Prompt: Think about what makes a test fair.

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

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  1. Question 1

    Why is it a good idea to repeat a test several times?

    • A. To change the answer
    • B. To make the test unfair
    • C. Because the first try never counts
    • D. To check the results are reliable

  2. Question 2

    Fair tests: which statement is true?

    • A. One try is always enough.
    • B. If a result surprises you, you should hide it.
    • C. A fair test means everyone gets a turn.
    • D. You should keep everything else the same.

  3. Question 3

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

  4. Question 4

    Mateo wants to know if plants grow better with more light. Which plan is fair?

    • A. Different plants, different water, different light
    • B. Same light for every plant
    • C. More water for the plant in the light
    • D. Same plant type, same water, different amounts of light

  5. Question 5

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

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

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

  7. Question 7

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

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

  8. Question 8

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

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

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Answer key: Planning a fair test

  1. 1. D. To check the results are reliable

  2. 2. D. You should keep everything else the same.

  3. 3. B. how tight and thick the strings are

  4. 4. D. Same plant type, same water, different amounts of light

  5. 5. A. the volume of water in each cup

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

  7. 7. A. the time for the sugar to dissolve

  8. 8. A. the type of paper towel