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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 thermometer / a ruler or tape measure / a measuring jug or cylinder / a stopwatch or timer) → 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 hot a cup of tea is / how long it takes to run 50 metres / how heavy a pet hamster is / how long an ice cube takes to melt) → how heavy a pet hamster isPrompt: 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 stopwatch / a thermometer / a rain gauge) → 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 amount of water / the type of paper towel / the size of the towel / the time he waits) → the type of paper towelPrompt: In a fair test you change only one thing: the thing you are testing.
  2. Aisha measures how fast sugar dissolves in water at different temperatures. What does she measure? (the temperature of the water / the time for the sugar to dissolve / the colour of the sugar / the type of cup) → 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. Ben tests whether salt water or tap water freezes faster. Which must he keep the same? (the volume of water in each cup / the time each one takes to freeze / the type of water / whether the water has salt) → the volume of water in each cupPrompt: He is changing the type of water and measuring the time.
  2. Fair tests: which statement is true? (If a result surprises you, you should hide it. / A fair test means everyone gets a turn. / In a fair test you change only one thing. / You should change as many things as possible.) → 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

    Fair tests: which statement is true?

    • A. You should keep everything else the same.
    • B. You should change as many things as possible.
    • C. A fair test means everyone gets a turn.
    • D. One try is always enough.

  2. Question 2

    Which question can be answered with a fair test?

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

  3. Question 3

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

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

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

  5. Question 5

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

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

  6. Question 6

    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 volume of water in each cup
    • D. the time each one takes to freeze

  7. Question 7

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

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

  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. A. You should keep everything else the same.

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

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

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

  5. 5. A. The drop height should be the same

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

  7. 7. C. Same plant type, same water, different amounts of light

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