ScienceWorking scientifically28 min★★ difficulty

Planning a fair test

Every fair investigation stands on three types of variable. Get them muddled and your results mean nothing.

Part of your national curriculum

Working scientifically: Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables

Lesson overview

What you'll learn in this lesson

Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables

Key learning points

• The three variables
• Choosing the enquiry type
• Worked example

This lesson at a glance

28 minutes
16 parts to scroll through
3 quick checks
Marked quiz at the end
Gentle pace: short sittings with pauses

Words to know

appropriatescientificenquirypredictionsidentifying

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Part 1 of 16 · Discover6%

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Part 1 of 16

Visual introduction

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Planning a fair test

Every fair investigation stands on three types of variable. Get them muddled and your results mean nothing.

In a nutshell

Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables

Learning cycle

Part 2 of 16

Learning cycle 1 of 2

Part 1 · The three variables

A short piece of teaching, then a check to make sure it has landed.

Explore the idea

Part 3 of 16

Learn

The three variables

The independent variable is what you deliberately change. The dependent variable is what you measure as a result. Control variables are everything else you keep the same, so any change in the dependent variable is really caused by the independent variable.

Reset break

Part 4 of 16

Pause

That's sitting 1 of 4 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now

Explore the idea

Part 5 of 16

Learn

Choosing the enquiry type

Some questions need a lab experiment (testing reaction rate with a thermometer), others need fieldwork (comparing plant density in shade and sun), and others need surveys or secondary data (average rainfall over years). Choosing the right type makes results meaningful.

Quick check

Part 6 of 16

Quick check

What is the independent variable?

Give me a hint

Quick check

Part 7 of 16

Quick check

Why keep control variables constant?

Give me a hint

Reset break

Part 8 of 16

Pause

That's sitting 2 of 4 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now

Learning cycle

Part 9 of 16

Learning cycle 2 of 2

Part 2 · Worked example

A short piece of teaching, then a check to make sure it has landed.

Explore the idea

Part 10 of 16

Learn

Worked example

Testing how surface area affects the rate a sugar cube dissolves: independent variable = surface area (whole cube vs crushed), dependent variable = time to dissolve, control variables = water volume, water temperature, stirring speed and mass of sugar.

Quick check

Part 11 of 16

Quick check

Which enquiry type suits comparing plant density in sun and shade?

Give me a hint

Reset break

Part 12 of 16

Pause

That's sitting 3 of 4 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now

Challenge round

Part 13 of 16

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

Challenge round

Part 14 of 16

Game · Recall cards

Dark beetles rise from 18% to 67%. What can be concluded directly?

Card 1 of 4

Mastery quiz

Part 15 of 16

Marked quiz

End of lesson quiz: Planning a fair test

4 questions, marked with the reasoning shown. No timer.

1. Dark beetles rise from 18% to 67%. What can be concluded directly?
2. What makes the model-beetle test fair?
3. Which conclusion is strongest?
4. What is the independent variable?

Lesson round-up

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Lesson round-up

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Part 1 of 16 · Watch & discover

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Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables