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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 tall a sunflower has grown? (a ruler or tape measure / a thermometer / weighing scales / 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 weighing scales? (how cold the water in a pond is / the mass of a bag of flour / how tall a sunflower has grown / the width of a leaf) → the mass of a bag of flourPrompt: What does this tool measure: length, temperature, mass, time or volume?
  3. Which is the best tool to find out how long it takes a snail to cross a table? (a ruler / a rain gauge / a stopwatch / a thermometer) → a stopwatchPrompt: "How long it takes" is about time.

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. Leo tests which paper towel soaks up the most water. What should he change? (the time he waits / the type of paper towel / the amount of water / the size of the towel) → the type of paper towelPrompt: In a fair test you change only one thing: the thing you are testing.
  2. Which question can be answered with a fair test? (Is a rainbow beautiful? / Who is the best scientist? / What is your favourite plant? / Does a heavier parachute fall faster?) → 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. Fair tests: which statement is true? (A fair test means everyone gets a turn. / One try is always enough. / 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.
  2. Mateo wants to know if plants grow better with more light. Which plan is fair? (Different plants, different water, different light / More water for the plant in the light / Same light for every plant / Same plant type, same water, different amounts of light) → Same plant type, same water, different amounts of lightPrompt: Only the thing being tested should change.

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

    Which question can be answered with a fair test?

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

  2. Question 2

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

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

  3. Question 3

    Fair tests: which statement is true?

    • A. One try is always enough.
    • B. You should change as many things as possible.
    • C. In a fair test you change only one thing.
    • D. A fair test means everyone gets a turn.

  4. Question 4

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

  5. Question 5

    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. the type of surface
    • D. nothing

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

  7. Question 7

    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. The drop height should be the same
    • D. Nothing, it is fair

  8. Question 8

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

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

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Answer key: Planning a fair test

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

  2. 2. C. the type of paper towel

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

  4. 4. A. how tight and thick the strings are

  5. 5. B. the height of the ramp

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

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

  8. 8. B. To check the results are reliable