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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 far a paper plane flew? (a ruler or tape measure / weighing scales / a measuring jug or cylinder / a thermometer) → 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 a stopwatch or timer? (how long an ice cube takes to melt / how tall a sunflower has grown / how cold the water in a pond is / how much milk is in a glass) → how long an ice cube takes to meltPrompt: 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? (weighing scales / a thermometer / a measuring jug / a metre stick (long ruler)) → 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. Why is it a good idea to repeat a test several times? (To check the results are reliable / Because the first try never counts / To make the test unfair / To change the answer) → To check the results are reliablePrompt: What if one result was a mistake?
  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 · 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. Which question can be answered with a fair test? (Who is the best scientist? / Does a heavier parachute fall faster? / What is your favourite plant? / Is a rainbow beautiful?) → Does a heavier parachute fall faster?Prompt: A fair test changes one thing and measures another.
  2. Priya tests which surface a toy car rolls furthest on. What must she keep the same? (the type of surface / nothing / how far the car rolls / the height of the ramp) → the height of the rampPrompt: Only the surface 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

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

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

  2. Question 2

    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. Different plants, different water, different light
    • D. Same light for every plant

  3. Question 3

    Fair tests: which statement is true?

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

  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. What is your favourite plant?
    • D. Who is the best scientist?

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

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

  7. Question 7

    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 change the answer
    • D. To make the test unfair

  8. Question 8

    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

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Answer key: Planning a fair test

  1. 1. A. the volume of water in each cup

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

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

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

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

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

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

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