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Science lesson plan · 3rd grade (Year 4 in England) · 30 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 · 4 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 / weighing scales / a thermometer / a ruler or tape measure) → a thermometerPrompt: 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? (the mass of a bag of flour / how far a paper plane flew / how much juice is in a carton / how long an ice cube takes to melt) → how far a paper plane flewPrompt: What does this tool measure: length, temperature, mass, time or volume?
  3. Which tool would show that the water in a bowl is getting colder? (a measuring jug / a ruler / a magnifying glass / a thermometer) → a thermometerPrompt: Colder means the temperature is going down.

Hook · 3 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 · 7 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 · 6 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? (More water for the plant in the light / Different plants, different water, different light / Same plant type, same water, different amounts of light / Same light for every plant) → 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? (What is your favourite plant? / Does a heavier parachute fall faster? / Is a rainbow beautiful? / 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 · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Leo tests which paper towel soaks up the most water. What should he change? (the amount of water / the size of the towel / the type of paper 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. Fair tests: which statement is true? (One try is always enough. / You should keep everything else the same. / You should change as many things as possible. / A fair test means everyone gets a turn.) → You should keep everything else the same.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/ 6

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

  2. Question 2

    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

  3. Question 3

    Fair tests: which statement is true?

    • A. Repeating a test helps you check your results.
    • B. If a result surprises you, you should hide it.
    • C. A fair test means everyone gets a turn.
    • D. You should change as many things as possible.

  4. Question 4

    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

  5. Question 5

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

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

  6. Question 6

    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 type of cup
    • C. the colour of the sugar
    • D. the temperature of the water

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Answer key: Planning a fair test

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

  2. 2. A. the type of paper towel

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

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

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

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