Science · Grade 4

Active learning ideas

Properties of Light: Refraction

Active learning helps students visualize abstract concepts like refraction by making light’s behavior visible and tangible. Hands-on experiments allow Grade 4 students to test ideas, compare observations, and correct misconceptions through direct experience rather than abstract explanation.

• Ontario Curriculum Expectations
• 4-PS4-2

• 25–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 25 min · Pairs

Pencil Pairs: Water Bend Observation

Pairs fill clear glasses halfway with water and place a pencil at an angle across each. Observe the pencil from side and top views, then remove it from water to compare. Sketch findings and discuss why the bend appears only at the water line.

Explain why a straw appears bent when placed in a glass of water.

Facilitation Tip

During Pencil Pairs, have students hold pencils vertically in empty glasses first, then in water-filled glasses, to notice the difference in appearance before discussing light paths.

What to look for

Provide students with a diagram showing a straw partially submerged in water. Ask them to draw the path of light rays to explain why the straw appears bent. Include the question: 'What property of light causes this effect?'

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Experiential Learning
• 40 min · Small Groups

Prism Small Groups: Rainbow Maker

Small groups direct sunlight through a triangular prism onto white paper, rotating it to spread colors. Record color order and try with flashlights in dim rooms. Predict changes with colored cellophane filters and test.

Design an experiment to demonstrate light refraction.

Facilitation Tip

For Prism Small Groups, provide each group with one prism and a flashlight to explore how light splits into colors, then rotate materials so students compare results.

What to look for

Hold up a glass of water with a pencil inside. Ask students to observe and then write down two sentences describing what they see and what they think is happening to the light.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 45 min · Small Groups

Lens Stations: Focus and Magnify

Set up stations with convex and concave lenses: one for focusing sunlight to a point, one for viewing text enlargement, one for image inversion. Groups rotate, measure focal lengths, and note bending directions.

Analyze how lenses use refraction to help us see.

Facilitation Tip

At Lens Stations, place magnifying glasses and reading lenses on labeled stands with clear instructions to observe how each lens changes the size or clarity of a printed image.

What to look for

Pose the question: 'How do lenses in eyeglasses help people see better?' Facilitate a class discussion where students explain the role of refraction and how lenses manipulate light to form clearer images.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Experiential Learning
• 35 min · Whole Class

Experiment Design: Whole Class Challenge

As a class, brainstorm variables like water depth or glass shape affecting bend amount. Pairs design and run one test, share data on chart paper. Vote on best explanation from results.

Explain why a straw appears bent when placed in a glass of water.

Facilitation Tip

For the Experiment Design challenge, guide students to start with a question like 'Which liquid makes a pencil appear most bent?' and record their predictions and observations in a shared chart.

What to look for

Provide students with a diagram showing a straw partially submerged in water. Ask them to draw the path of light rays to explain why the straw appears bent. Include the question: 'What property of light causes this effect?'

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Teaching refraction works best when students first observe surprising phenomena, then construct explanations through guided inquiry. Avoid starting with definitions; instead, let students describe what they see before introducing terms like ‘refraction’ and ‘angle of incidence.’ Research shows students learn more when they must predict outcomes before testing, so always ask, 'What do you think will happen?' before conducting activities. Use student drawings and verbal explanations as assessment tools throughout the lesson, not just at the end.

Students will explain that light bends when it changes speed between materials, describe how prisms and lenses manipulate light, and apply refraction principles to real-world optical devices like eyeglasses. They should use scientific terms such as ‘boundary,’ ‘bend,’ and ‘density’ accurately in discussions and drawings.

---

Watch Out for These Misconceptions

• During Pencil Pairs, watch for students who believe the pencil actually bends or breaks in water. Redirect them by asking, 'Place a dry pencil next to the one in water. What do you notice about the real shape?' Then have them draw the light rays moving from air to water to explain the illusion.

  During Pencil Pairs, students compare the pencil’s shape in air and water to confirm it remains straight. Have them trace the pencil’s outline on paper, then draw light rays bending at the water’s surface to show how the illusion forms.

• During Prism Small Groups, some students may think refraction only happens in water. After testing water with a pencil, provide prisms and oils to observe bends in glass and gel, then ask, 'How is this like the pencil in water? How is it different?' to highlight the general rule.

  During Prism Small Groups, students rotate through materials like glass prisms, oils, and gels to observe refraction in each. After each station, ask them to compare the bend angles and note that all materials with different densities cause refraction, not just water.

• During Prism Small Groups, students might think prisms paint colors onto light. Ask them to predict the order of colors before testing, then have groups share their observations to confirm the fixed sequence matches the rainbow pattern in sunlight.

  During Prism Small Groups, students predict the color order before using a prism and sunlight. After observing the fixed sequence, ask them to explain why colors appear in this order, linking it to how each wavelength bends differently.

---

Methods used in this brief

• Experiential Learning