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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 the mass of a bag of flour? (a thermometer / weighing scales / a stopwatch or timer / a measuring jug or cylinder) → weighing scalesPrompt: Is it a length, a temperature, a mass, a time or an amount of liquid?
  2. What could you measure with a thermometer? (how much water a plant is given / how long a toy car takes to roll down a ramp / how long a worm is / how cold the water in a pond is) → how cold the water in a pond isPrompt: 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 magnifying glass / a ruler / a measuring jug / a thermometer) → a thermometerPrompt: Colder means the temperature is going down.

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. Isla tests which ball bounces highest. She drops one ball from 1 m and another from 2 m. What is wrong? (The drop height should be the same / Nothing, it is fair / She should not measure the bounce / She should use only one ball) → The drop height should be the samePrompt: What is she trying to compare?
  2. Ben tests whether salt water or tap water freezes faster. Which must he keep the same? (the type of water / the time each one takes to freeze / whether the water has salt / the volume of water in each cup) → the volume of water in each cupPrompt: He is changing the type of water and measuring the time.

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. Leo tests which paper towel soaks up the most water. What should he change? (the size of the towel / the amount of water / the time he waits / the type of paper towel) → 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? (If a result surprises you, you should hide it. / You should change as many things as possible. / Repeating a test helps you check your results. / 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

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

  2. Question 2

    Fair tests: which statement is true?

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

  3. Question 3

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

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

  4. Question 4

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

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

  5. Question 5

    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

  6. Question 6

    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 type of cup
    • D. the time for the sugar to dissolve

  7. Question 7

    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

  8. Question 8

    Which question can be answered with a fair test?

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

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Answer key: Planning a fair test

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

  2. 2. D. You should keep everything else the same.

  3. 3. D. Same plant type, same water, different amounts of light

  4. 4. D. the height of the ramp

  5. 5. B. the type of paper towel

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

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

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