Colour & Frequency

Overview

Lesson 10 of 25 continues the “Exploring the World of Waves” unit by linking wave behaviour to light appearance. Students use the PhET “Color Vision” simulation and simple LED/spectroscope observations to explain how wavelength (frequency) affects colour.

Learning intentions

Students will:

• investigate how monochromatic light (single wavelength) produces specific perceived colours
• relate changes in wavelength to changes in colour and brightness in simulated and real light
• analyse and communicate findings using a clear scientific process

Success criteria

Students can:

• describe the relationship between wavelength and the colour seen (for both virtual and real sources)
• explain why white light appears as a spread of wavelengths and how that differs from monochromatic light
• use measurements/observations to justify claims about light frequency and colour mixing
• present results clearly in a digital colour wheel and short reflection

Curriculum links

• PY-11-02: Students explain the properties and behaviours of waves by applying wave ideas to light (wavelength, frequency and behaviours such as dispersion/spectral composition).
• PY-11WS-06: Students use scientific process to solve scientific problems by planning, conducting and communicating investigations with evidence.
• PY-11WS-04: Students select and process qualitative and quantitative data by recording observations from simulation and instruments and using them to draw conclusions.

Lesson structure (45 minutes)

1. 0–5 min · Hook (demo + question). Teacher shows two LEDs: one narrow colour (monochromatic-looking) and one broader “white” LED; students record which looks “single colour” versus “mixed”. Students answer: “What does the appearance of colour suggest about the wavelengths in the light reaching your eyes?”

2. 5–12 min · Setup & safety briefing. Teacher models the equipment routine (spectroscope handling, no direct bright viewing, careful note-taking) and logs the workstation expectations. Students complete a quick lab checklist and open the simulation on their device while the teacher circulates.

3. 12–22 min · Simulation investigation (guided). Teacher instructs students to run PhET “Color Vision” focusing on monochromatic light (single wavelength) and then switch to white light to observe photon distribution and perceived colour. Students record in a table: wavelength setting, perceived colour, and a short “evidence statement” describing what they saw in the simulation (e.g., photons/colour output).

4. 22–30 min · Hands-on spectroscope check. Teacher sets up stations with an LED array and handheld spectroscopes; each group tests at least two LEDs (one narrow-ish, one broader/white). Students observe and sketch the spectrum appearance (bands/lines vs a wider spread) and link that to the colour they observe.

5. 30–38 min · Colour wheel build (key task). Teacher provides a template for a “digital colour wheel” where each segment is labelled with an approximate wavelength range used from simulation and/or observations. Students create/update the wheel: assign colours to segments using their wavelength–colour evidence, then add a claim: “Wavelength determines colour because…”

6. 38–43 min · Compare & conclude (mini-analysis). Teacher asks guiding prompts: “How did monochromatic results differ from white light?” and “What does this suggest about wave composition of light?” Students complete a short CER paragraph (Claim–Evidence–Reasoning) comparing simulation evidence with spectroscope evidence.

7. 43–45 min · Exit ticket (formative check). Teacher collects a one-question exit ticket: “Explain, using wave ideas, why different wavelengths produce different colours.” Students submit before leaving; teacher quickly scans responses for misconceptions (e.g., confusing brightness with wavelength, or treating colour as fixed to source labels).

Resources

• PhET “Color Vision” simulation loaded on student devices
• Device/simulation worksheet template (wavelength, colour, evidence)
• LED array(s): at least two types (monochromatic or narrow band; one broader/white)
• Handheld spectroscopes
• Printed/accessible safety reminders for bright LEDs
• Digital colour wheel template (teacher-provided) or editable document
• Lab notebook or data table sheet
• Station timer (optional)

Assessment

• Formative during simulation: teacher checks recorded wavelength–colour pairs for correctness and completeness.
• Formative during hands-on: teacher listens for correct links between spectrum shape (lines/bands vs broad spread) and colour perception.
• Exit ticket: evaluates whether students can explain the wavelength–colour relationship using wave properties and reasoning.

Differentiation

• Support: sentence starters for CER (“My claim is…”, “My evidence is…”, “This makes sense because waves…”); a partially completed colour wheel for students needing scaffolds.
• Support: provide a wavelength-to-colour guide as a reference card (for approximate matching only), while still requiring students to justify using their own observations.
• Extension: challenge students to predict the colour of an intermediate wavelength by interpolating between two simulation observations, then verify in the simulation.
• EAL/SEN: allow diagrams/symbols in place of some text; pair students strategically for collaborative recording and wheel construction.