Years 3–6 · Week 2 of 12
Light, Colour and Photons
Learning goals
By the end, you can…
- Explain that light carries energy.
- Use wave ideas to compare colours of visible light.
- Describe a photon as one quantum of light energy.
- Explain why a photon icon is not a picture of a tiny coloured ball.
What you already know
Connect to a familiar idea
You have seen light spread from a lamp and colours appear in a rainbow. Light can warm an object and carry information to your eyes.
- Recognise some colours in the visible rainbow.
- Know that diagrams can be models rather than photographs.
Opening story
Start with something familiar
A raindrop can separate sunlight into many colours. A sensitive detector can also record light one energy event at a time. Quantum physics helps us connect these two kinds of evidence.
Plain-English explanation
Build the idea carefully
Light carries energy
Light carries energy from one place to another. Wave ideas help describe light, and visible colours have different wavelengths and frequencies.
Waves, colours and photons
Light exchanges energy with matter in quanta called photons. A photon icon counts a detection or energy-transfer event; it is not a snapshot of a tiny coloured ball.
Try the model
Explore a light model
Choose a visible colour, compare the wave spacing, then send photon events to the detector.
Ready. Adjust a control, then run the model.
What this model shows: The wave and photon displays are linked teaching models. The photon symbols count events and do not show photon shape or colour.
Text alternative for this interactive
Compare the red and blue wave cards, then count ten detector-event symbols.
Expected observation: Changing colour changes the modelled wave spacing, while the detector still records separate photon events.
Guided activity
Wave view and detector view
- Choose two colours and compare their wave traces.
- Predict what the photon counter will show after ten events.
- Run the counter and describe what the wave view and event view each show.
Evidence to collect: The colour setting changes the wave model, and the counter increases one whole detection event at a time.
Glossary
Words to know
- light
- Electromagnetic radiation that carries energy.
- wavelength
- The distance between matching points in a repeating wave pattern.
- photon
- One quantum of electromagnetic energy.
- detector
- A device that records an interaction or event.
Short recap
Keep these ideas
- Light carries energy.
- Wave ideas help describe colour and other patterns.
- Photons describe individual light-energy exchanges, not tiny coloured balls.
Knowledge check
4 clear questions
Choose an answer for immediate feedback. You may retry, and your best submitted score is kept.
Explore More Optional extension for Years 5–6
For visible light, colour is connected to wavelength and frequency. A blue photon has more energy than a red photon, but both are quantum objects rather than coloured marbles.
Try this
Order red, green and blue wave cards by wavelength. Then explain why the photon icons must carry a model warning.
Adult support Teacher and parent notes
Discuss
- Ask what evidence a wave trace shows and what a detector count shows.
- Avoid saying that light switches between being a wave and being a ball.
- Treat colour outside human vision carefully: ultraviolet and infrared are not visible colours.
Answer guidance
Strong answers say that wave and photon descriptions predict different features of experiments and that neither classroom picture is complete.
Offline activity
Make paper wave strips with different spacing and use counters as detector events. Keep the event-symbol warning visible.
Safety
Never look at the Sun or point lasers at eyes. Use screen models, paper colours or an ordinary enclosed classroom light source.
Sources and further reading
Checked references for this lesson
These sources support the lesson’s main scientific claims. Links open on the source organisation’s site.
- Wave-Particle Duality OpenStax, Rice University · open textbook · checked 2026-08-02
- Quantum information science National Institute of Standards and Technology · government explainer · checked 2026-08-02
- Basics of Quantum Information IBM Quantum Learning · official course · checked 2026-08-02
Content review: Reviewed on 2026-08-02.