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.
- Which tool would you use to measure how much juice is in a carton? (a measuring jug or cylinder / a ruler or tape measure / weighing scales / a stopwatch or timer) → a measuring jug or cylinderPrompt: Is it a length, a temperature, a mass, a time or an amount of liquid?
- What could you measure with a measuring jug or cylinder? (how tall a sunflower has grown / how long an ice cube takes to melt / how much water a plant is given / how long it takes to run 50 metres) → how much water a plant is givenPrompt: What does this tool measure: length, temperature, mass, time or volume?
- Zara wants to know if her bean plant grows taller each day. What should she use? (weighing scales / a ruler / a thermometer / a stopwatch) → a rulerPrompt: She wants to know how tall it is.
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.
- Leo tests which paper towel soaks up the most water. What should he change? (the amount of water / the type of paper towel / the time he waits / the size of the towel) → the type of paper towelPrompt: In a fair test you change only one thing: the thing you are testing.
- Ben tests whether salt water or tap water freezes faster. Which must he keep the same? (whether the water has salt / the volume of water in each cup / the type of water / the time each one takes to freeze) → the volume of water in each cupPrompt: He is changing the type of water and measuring the time.
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.
- 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.
- Fair tests: which statement is true? (You should change as many things as possible. / You should keep everything else the same. / If a result surprises you, you should hide it. / One try is always enough.) → 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