Reflecting colour
Lesson details
Learning outcome
I can explain the colour of an object in white light and in coloured light.
Key learning points
- Colour is detected in the eye by the R, G and B ‘cone cells’ that each detect a range of colours of light.
- The colour of an object in white or coloured light depends on the amounts of R, G and B light it is reflecting.
- White objects reflect all colours of light so look the same colour as the incident light (whether white or coloured).
- The colours of light that an object does not reflect are absorbed. Black objects absorb all colours of light.
- In red/green/blue light, an object will appear red/green/blue if it reflects that colour, and black if it does not.
Keywords
Reflect - to hit a surface and ‘bounce’ off
Incident - a word used to describe the incoming light that hits a surface
Scatter - to reflect light in many directions at once
Cone cell - the cells at the back of the eye that detect colour
Absorb - a material that absorbs light / gains energy from light travelling through it, decreasing the amount of light
Common misconception
Colour is the sum of the colour of the object and the colour of light falling on it.
Use coloured lights to show that red coloured objects reflect red light, but not blue or green.
Teacher tip
Projecting a slide of pure red, green or blue onto a screen enables objects’ colours to be seen when they are lit up by each primary colour in turn (e.g. for the demonstration in Task B). This is particularly convincing if you have a very good blackout in your room.
Equipment
For task B: a colour printed 'flag of Guyana', a source of green light e.g. a projector connected to a laptop to project a slide of green light
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of the following words means ‘reflect light in many directions at once’?
Q2.A person sees a book. Which of the following statements explains how they see the book?
Q3.Which of the following colours is seen when blue and red light of equal brightness enter the eye of a person who has full colour vision?
Q4.Which of the following colours is seen when red and green light of equal brightness enter the eye of a person who has full colour vision?
Q5.Which of the following are names of types of cells in the retina of the eye?
Q6.Which of the following are colours that can only be seen when light of more than one colour enters the eye?
Assessment exit quiz
6 Questions
Q1.Which of the following statements explains why a black object looks black?
Q2.Which of the following statements explains why a white piece of paper looks white when white light shines on it?
Q3.Using the RGB model of white light, we can represent white light using only red, green and blue rays. What does each colour of ray represent?
Q4.Why does a white piece of paper look cyan when cyan light shines on it?
Q5.Inside a room with no windows, the only light shining is a green light. Which of the following objects in the room look green?
Q6.Inside a room with no windows, there is a lamp shining. The light from the lamp looks magenta. Match each object in the room with the colour it appears to be.
To help you plan your 8 science lesson on: Reflecting colour, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 8 science lesson on: Reflecting colour, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 science lessons from the Making images unit, dive into the full secondary science curriculum, or learn more about lesson planning.