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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 warm the classroom is? (a measuring jug or cylinder / a stopwatch or timer / a thermometer / weighing scales) → a thermometerPrompt: Is it a length, a temperature, a mass, a time or an amount of liquid?
  2. What could you measure with weighing scales? (how warm the classroom is / how long a candle burns / the mass of a pumpkin / how long it takes to run 50 metres) → the mass of a pumpkinPrompt: 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) / a thermometer / 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. Mateo wants to know if plants grow better with more light. Which plan is fair? (Different plants, different water, different light / Same plant type, same water, different amounts of light / Same light for every plant / More water for the plant in the 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 temperature of the water / the type of cup / the colour of the sugar) → the time for the sugar to dissolvePrompt: She changes the temperature. What does she then look at?

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. 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. Fair tests: which statement is true? (In a fair test you change only one thing. / You should change as many things as possible. / One try is always enough. / If a result surprises you, you should hide it.) → In a fair test you change only one thing.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

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

  2. Question 2

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

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

  3. Question 3

    Fair tests: which statement is true?

    • A. A fair test means everyone gets a turn.
    • B. If a result surprises you, you should hide it.
    • C. One try is always enough.
    • D. Repeating a test helps you check your results.

  4. Question 4

    Which question can be answered with a fair test?

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

  5. Question 5

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

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

  6. Question 6

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

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

  7. Question 7

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

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

  8. Question 8

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

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

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Answer key: Planning a fair test

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

  2. 2. B. the height of the ramp

  3. 3. D. Repeating a test helps you check your results.

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

  5. 5. D. the type of paper towel

  6. 6. C. the volume of water in each cup

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

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