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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 stopwatch or timer / weighing scales / a thermometer) → 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 long an ice cube takes to melt / how much water a plant is given / how long a toy car takes to roll down a ramp / the width of a leaf) → the width of a leafPrompt: 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 stopwatch / a ruler / a thermometer) → a rulerPrompt: She wants to know how tall it is.

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. 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. 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.

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. 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. Fair tests: which statement is true? (Repeating a test helps you check your results. / A fair test means everyone gets a turn. / If a result surprises you, you should hide it. / One try is always enough.) → Repeating a test helps you check your results.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

Name

Date

Score/ 8

  1. Question 1

    Fair tests: which statement is true?

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

  2. Question 2

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

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

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

  4. Question 4

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

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

  5. Question 5

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

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

  6. Question 6

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

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

  7. Question 7

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

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

  8. Question 8

    Which question can be answered with a fair test?

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

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Answer key: Planning a fair test

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

  2. 2. A. Same plant type, same water, different amounts of light

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

  4. 4. A. To check the results are reliable

  5. 5. B. the height of the ramp

  6. 6. B. the type of paper towel

  7. 7. B. the volume of water in each cup

  8. 8. B. Does a heavier parachute fall faster?