Good Learning Co.
SavannahYear 8
← Science
ScienceGravity and light30 min★★★ difficulty

Light: reflection, refraction and colour

Light travels in straight lines until something changes its direction. Reflection, refraction and the spectrum all follow from that, and ray diagrams are how you prove you understand it.

Part of your national curriculum
  • Physics: waves: Understand the transmission of light through materials, reflection, refraction and the colours of the light spectrum

Lesson overview

What you'll learn in this lesson

Understand the transmission of light through materials, reflection, refraction and the colours of the light spectrum

Key learning points

  • • Reflection and ray diagrams
  • • Refraction
  • • Transmission, absorption and scattering
  • • Colour

This lesson at a glance

  • 30 minutes
  • 19 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

transmissionmaterialsreflectionrefractioncolours

Scroll down — the lesson carries on below

Part 1 of 19 · Discover5%
1

Watch & discover

Part 1 of 19

Watch first

Light: reflection, refraction and colour

See how light reflects, passes through, bends and scatters.

Do it for real

The practicals below use what the film shows, with a full method you can follow at home.

What actually changes a pendulum's swing?Bending light and splitting white light

In a nutshell

Understand the transmission of light through materials, reflection, refraction and the colours of the light spectrum

2

What you already know

Part 2 of 19

Before we start

What you already know

You should know light travels in straight lines and can be reflected by a mirror.

Recap: Mass, weight and gravity
3

Key words

Part 3 of 19

Key words

Words you'll need today

Reflection
Light bouncing off a surface; angle of incidence equals angle of reflection.
Refraction
Light changing direction when it enters a different material at an angle.
Normal
A construction line drawn at 90 degrees to the surface.
Transparent
Transmitting light so objects can be seen clearly through it.
Spectrum
The band of colours white light separates into.
4

Learning cycle

Part 4 of 19

Learning cycle 1 of 2

Reflection and refraction

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

5

Explore the idea

Part 5 of 19

Learn

Reflection and ray diagrams

Draw the normal at 90 degrees to the mirror where the ray hits. The angle of incidence, measured from the normal, equals the angle of reflection. Angles are always measured from the normal, never from the surface - that single habit fixes most lost marks. A smooth surface gives a clear image; a rough one scatters light in all directions.

6

Explore the idea

Part 6 of 19

Learn

Refraction

Light slows when it enters glass or water, so a ray entering at an angle bends towards the normal, and bends away again on leaving. This is why a straw looks broken in a glass and a pool looks shallower than it is. A ray hitting the surface along the normal slows but does not change direction, because there is no angle to bend.

7

Quick check

Part 7 of 19

Quick check

In reflection, the angle of incidence...

8

Quick check

Part 8 of 19

Quick check

Light entering glass at an angle bends...

9

Reset break

Part 9 of 19

Pause

That's sitting 1 of 2 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
10

Learning cycle

Part 10 of 19

Learning cycle 2 of 2

Colour and materials

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

11

Explore the idea

Part 11 of 19

Learn

Transmission, absorption and scattering

Transparent materials transmit light with little scattering; translucent materials such as frosted glass scatter it, so you see light but not a clear image; opaque materials absorb or reflect it all. Whether you can see through something is about scattering, not just about how much light gets through.

12

Explore the idea

Part 12 of 19

Learn

Colour

A prism refracts each colour by a slightly different amount, so white light separates into red, orange, yellow, green, blue, indigo and violet - red bends least, violet most. An object looks red because it reflects red light and absorbs the rest, so a red jumper under pure blue light looks almost black: there is no red light there to reflect.

13

Quick check

Part 13 of 19

Quick check

Frosted glass is best described as...

14

Quick check

Part 14 of 19

Quick check

A red jumper under blue light appears...

15

Common mix-ups

Part 15 of 19

Common mix-ups

Things people often get wrong

  • Angles are measured from the normal, not from the surface.
  • Refraction is a change in direction caused by a change in speed, not by bouncing.
  • Coloured objects do not create colour; they reflect some and absorb the rest.
  • A ray entering along the normal does not bend.
16

Challenge round

Part 16 of 19

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

17

Challenge round

Part 17 of 19

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

The angle of incidence, measured from the normal, equals the angle of ____.

Transparent ____ transmit light with little scattering; translucent materials such as frosted glass scatter it, so you see light but not a clear image; opaque materials absorb or reflect it all.

18

Mastery quiz

Part 18 of 19

Marked quiz

End of lesson quiz: Light: reflection, refraction and colour

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

  1. 1. The normal is drawn...

  2. 2. Which colour refracts most in a prism?

  3. 3. A rough surface causes...

  4. 4. An opaque object...

  5. 5. A straw looks bent in water because of...

  6. 6. A white object reflects...

19

Lesson round-up

Part 19 of 19

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 19 · Watch & discover

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    Understand the transmission of light through materials, reflection, refraction and the colours of the light spectrum

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