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Oak National Academy
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Year 8

Seeing in colour

I can state the primary colours of light, describe how they mix to produce other colours, and explain how the eye detects colour.

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New
New
Year 8

Seeing in colour

I can state the primary colours of light, describe how they mix to produce other colours, and explain how the eye detects colour.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. All colours of light can be created by mixing the primary colours of light; red, green and blue.
  2. Mixing equal amounts of two primary colours creates a secondary colour. All three mixed in equal amounts makes white.
  3. The retina, on the back of the eye, detects light. When there is no light, we see black.
  4. On the retina, three types of cone cell detect either red, green or blue light, and rod cells detect brightness.
  5. Display screens are made of tiny red, green and blue lights (pixels) which vary in brightness to make different colours.

Common misconception

Colour is something different to light. The colours of light will mix in the same way that paints of different colours mix.

Show pupils how different colours of light can combine to produce different colours, including white light.

Keywords

  • Primary colour - The colours of light from which all other colours of light can be made (red, green and blue).

  • Secondary colour - Colours of light that are made by mixing two primary colours in equal amounts.

  • Retina - The back surface of the eye that detects light.

  • Cone cell - The cells at the back of the eye that detect colour.

  • Rod cell - The cells at the back of the eye that detect brightness.

Build understanding about colour slowly and don't make assumptions as to what pupils already understand. Many websites and apps are available that allow you to control the amounts of R, G and B emitted. Be aware that up to 8% of males and 0.5% of females may be affected by colour blindness.
Teacher tip

Equipment

Ray boxes and coloured filters (or red, green and blue LED light sources) for mixing colours of light.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

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).

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Starter quiz

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6 Questions

Q1.
A room is completely dark inside. Which of the following statements explains why?
The room is full of blackness.
Correct answer: There is no light in the room.
The light in the room is colourless.
All of the light is being sucked out of the room.
Q2.
Which of the following must happen for us to see a real object?
The object must be making light.
Light must travel from our eyes to the object.
Correct answer: Light must travel from the object to our eyes.
All of the light from the object must enter our eyes.
Q3.
Which of the following explains how we see text and pictures displayed on a computer screen or phone screen?
Light reflects off the screen into our eyes.
Correct answer: Light emitted by the screen enters our eyes.
Light emitted by our eyes hits the screen and returns to our eyes.
Q4.
Sort the following statements into the correct order to describe what happens when we see an object with our eye.
1 - Light travels from the object to our eye.
2 - The light passes through the pupil.
3 - The light is focused by the lens.
4 - The light reaches the retina.
5 - Signals are sent to the brain.
Q5.
Which of the following colours are often described as the three primary colours of paint, which can be mixed to make many other colours of paint?
Correct answer: blue
orange
green
Correct answer: red
Correct answer: yellow
Q6.
Which of the following words means ‘brightness’ when it is used to describe light?
colour
density
gravity
Correct answer: intensity
spectrum

Exit quiz

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6 Questions

Q1.
Which of the following are the primary colours of light?
Correct answer: blue
Correct answer: green
magenta
Correct answer: red
yellow
Q2.
Which of the following are the secondary colours of light?
Correct answer: cyan
green
Correct answer: magenta
orange
Correct answer: yellow
Q3.
Which of the following colours is seen by people who do not have colour blindness if equal amounts of blue light and green light are mixed?
Correct answer: cyan
magenta
red
white
yellow
Q4.
How does a typical computer or mobile phone screen show a grey rectangle?
It switches off all pixels in the rectangle.
It switches on all the grey pixels in the rectangle.
It switches on all the pixels of two colours in the rectangle.
Correct answer: It switches on all pixels in the rectangle at equal intensities.
Q5.
Match each part of the eye with its description.
Correct Answer:retina,the back surface of the eye that detects light

the back surface of the eye that detects light

Correct Answer:cone,type of cell at the back of the eye that detects colour

type of cell at the back of the eye that detects colour

Correct Answer:rod,type of cell at the back of the eye that detects brightness

type of cell at the back of the eye that detects brightness

Q6.
Which of the following statements is correct?
Mixing yellow light and blue light makes green light.
Correct answer: Adding a second colour of light to a first makes a lighter or brighter colour.
It is impossible to mix primary colours of light to make light that looks brown.

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