Light Wave Exploration

Overview

In this lesson, students introduce light as a wave by investigating how light rays behave when they meet boundaries. They use the PhET “Bending Light” simulation (refraction and reflection) alongside teacher-led laser and prism demonstrations, then connect observations to measurable predictions.

Learning intentions

Students will:

• Explain how light can be modelled as rays that show wave-like behaviours at interfaces.
• Describe and use the terms incident ray, reflected ray, refracted ray, normal, and angle of incidence.
• Predict and test how changing angles and materials affects reflection and refraction using simulation and physical models.
• Use scientific process to solve a specific optical problem and communicate findings clearly.

Success criteria

Students can:

• Identify reflected and refracted rays in both simulation and real demonstrations.
• Use evidence from results to justify claims about how incident angle and material change the refracted angle.
• Record observations/data accurately and explain patterns in words and simple diagrams.
• Evaluate whether their predictions match results and suggest one improvement to the investigation.

Curriculum links

• PY-11-02: Students explain the properties and behaviours of waves by applying wave behaviours to light.
• PY-11WS-01: Students develop and evaluate a question/hypothesis and link predictions to an investigation.
• PY-11WS-06: Students use scientific process to solve scientific problems and communicate conclusions.

Lesson structure (45 minutes)

1. 0–5 min · Hook and model prompt. Teacher shows a short “bending” scenario (laser into transparent block/prism) and asks students to predict what happens to the beam as it enters and exits. Students do a quick think-pair-share and write one prediction.

2. 5–12 min · Direct teach: ray model + wave behaviour. Teacher introduces the language of refraction/angle measurement using a diagram (incident ray, reflected ray, refracted ray, normal) and links it to wave behaviour at boundaries (bending due to speed change in different media). Students sketch a labelled diagram and complete two guided prediction statements (e.g., “If the incident angle increases, the refracted angle will…”).

3. 12–20 min · Simulation exploration: Bending Light. Teacher sets the task: in PhET “Bending Light”, students select a medium boundary, then vary the angle of incidence and observe reflected and refracted angles. Students use tablets/laptops (pairs) to record at least two trials in a table: incident angle, reflected direction, refracted angle, and a brief note of any pattern.

4. 20–28 min · Physical demonstration: laser + prism/rectangular block. Teacher demonstrates a laser passing into and out of a prism or block, projecting the rays onto paper for safe angle observation. Students identify where reflection happens, where refraction happens, and compare the direction of the refracted ray to their simulation pattern.

5. 28–37 min · Mini investigation challenge (problem-solving). Teacher provides a structured prompt: “Choose a target refracted angle (e.g., ‘aim for a smaller/ larger bend’). Adjust the incident angle to achieve it, then state the relationship you notice.” Students iterate in simulation or with a simple angle-measurement diagram, record what worked, and update their hypothesis if needed.

6. 37–44 min · Evaluate evidence and communicate. Teacher models how to write a 3–4 sentence conclusion: claim, evidence (from trials), explanation (boundary effect), and evaluation (match/mismatch + reason). Students complete a conclusion paragraph on their worksheet and add one improvement suggestion.

7. 44–45 min · Exit ticket. Students answer: “In your own words, what causes light to bend when it enters a new material?” and “One piece of evidence from today supports your answer.”

Resources

• PhET “Bending Light” simulation (device lab or teacher device + student pairs)
• Printed worksheet with ray diagram, data table, and conclusion scaffold (one per student)
• Laser pointer, transparent block/prism, protractor/ruler, white paper or ray screen (teacher set-up)
• Safety eyewear for demonstration viewing (if required by school policy)
• Angle measurement tools and pens
• Timer and grouping cards for pairs/groups

Assessment

• Formative: teacher checks during simulation for correct identification of incident/reflected/refracted rays and sensible recording of angles.
• Formative: students’ hypothesis/prediction statements at the start of the challenge are reviewed for clarity and testability.
• Summative for the lesson: exit ticket responses plus worksheet conclusion for evidence-based reasoning.

Differentiation

• Support: provide sentence starters for predictions and conclusions (e.g., “My evidence shows…”, “This pattern suggests…”), plus a partially labelled ray diagram.
• Support: offer an “angle-word bank” (incident, normal, refracted) and a worked example of how to record one trial.
• Extension: students compare two different boundaries/materials in the simulation and state how results differ (qualitatively and using at least one data point).
• EAL/SEN: allow diagram-first responses; key terms are consistent on the worksheet and in the teacher diagram; comprehension checks occur in pair work.

Brief teacher notes (immediate)

• Reinforce: reflection angle equals incidence angle (in the simulation when applicable) and refraction involves a change in direction when entering a different medium.
• Keep physical demonstration quick and focus on identifying ray changes rather than complex calculations.