Year 6

Variables in electric circuits: do and review

I can investigate variables that may affect the brightness of a bulb in an electric circuit.

Year 6

Variables in electric circuits: do and review

I can investigate variables that may affect the brightness of a bulb in an electric circuit.

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Lesson details

Key learning points

  1. Equipment such as a light sensor and data logger can be used to measure bulb brightness in lux.
  2. Scientists use the results from investigations to support or reject scientific ideas and theories.
  3. Adding bulbs means that voltage is equally distributed among them all, so bulbs will be dimmer.
  4. A bulb will be the same brightness wherever you place it in a circuit.

Common misconception

Pupils may not understand how variables interact within a circuit and how changes in one variable can affect others.

Teaching slides will explain that like in science experiments variables are controlled for fair tests, the same can be done in circuits when adjusting variables like voltage to see how they affect things like brightness or speed.


  • Circuit - An electrical circuit is a closed loop or path that electricity can flow through to make an object work.

  • Variable - A variable is a factor that can be changed in an investigation.

  • Brightness - The brightness of a bulb is the amount of light it produces.

  • Affect - To affect something or someone is to change it or how it behaves.


Equipment for building and investigating simple circuits with bulbs including cells, wires and switches. Equipment will also be needed to measure the brightness of light.

Content guidance

  • Equipment requiring safe usage.


Adult supervision recommended.


This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).



6 Questions

What is the name for something that can be changed in an investigation?
Correct answer: variable
Which of these is not a component of an electrical circuit?
Correct answer: engine
Correct answer: pulley
What component is shown here?
An image in a quiz
Correct Answer: buzzer, a buzzer
In which of these circuits would the bulb produce light?
circuit 1
Correct answer: circuit 2
Which of these cells would provide the smallest electrical push to a circuit?
Correct answer: cell 1
cell 2
Why should you only change one variable in an investigation?
It makes it easier to do the investigation.
Correct answer: It allows you to work out what has caused an effect.
It allows you to complete the investigation quickly and efficiently.

6 Questions

What do you call the equipment that detects the brightness of bulbs?
light reader
light bulb
Correct answer: light sensor
light valuer
Which part of an investigation do scientists use to decide whether to support or reject a scientific theory?
Correct Answer: results, data
True or false? These results support the idea that adding bulbs reduces the brightness of a bulb.
An image in a quiz
Correct Answer: false
If you have 8 volts push in a circuit and 4 bulbs, how many volts will each bulb receive?
An image in a quiz
Correct answer: 2
How can you make a bulb brighter in a circuit?
An image in a quiz
add more bulbs
Correct answer: remove bulbs
remove cells
What happens to the brightness of a bulb in a circuit if you position it closer to the cell?
It gets brighter.
It gets dimmer.
Correct answer: It does not change.

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