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What Light Teaches

  • Reflection: Mirrors; bouncing light.
  • Refraction: Light bending through water or glass.
  • Dispersion: White light = all colors.
  • Color mixing: Primary colors; additive vs subtractive.
  • Shadows: Object blocking light path.
  • Speed of light (advanced): Why we see stars from the past.

Foundational physics topic for upper elementary.

The Short Answer

AgeExperimentSupplies
4–5Shadow tracingChalk or paper
4–6Pencil in waterPencil + glass
5–7Prism rainbowPrism ($5)
6–8Color mixingFood coloring + water
7–9Flashlight + filtersFlashlight + colored cellophane
8–10Mirror reflection puzzlesSmall mirrors ($15)
10+Pinhole cameraCardboard box + wax paper

Reflection Experiments (3)

1. Mirror Reflection Test (Ages 5+)

Materials: Small mirror, toy object Steps:

  1. Place mirror perpendicular to table.
  2. Kid places toy in front.
  3. Predict: which side will the reflection show? Left or right?
  4. Test.

Learning: Mirror reflection reverses left-right.

2. Light Bouncing (Ages 7+)

Materials: 2–3 small mirrors, flashlight, dark room Steps:

  1. Aim flashlight at first mirror.
  2. Position 2nd mirror to catch reflection.
  3. Position 3rd to bounce again.
  4. Can you get light to travel around a corner?

Learning: Light travels in straight lines; mirrors redirect.

3. Periscope Construction (Ages 9+)

Materials: Cardboard tubes, 2 mirrors, tape Steps:

  1. Cut angled holes in cardboard tube.
  2. Insert mirrors at 45° angles.
  3. Look through bottom; see over walls.

Learning: Double-reflection application.

Refraction Experiments (3)

4. Pencil in Water (Ages 4+)

Materials: Pencil, clear glass of water Steps:

  1. Put pencil half-in water.
  2. Look from side.
  3. Pencil appears bent.

Learning: Light bends when passing between water and air.

5. Disappearing Coin (Ages 6+)

Materials: Clear glass, water, coin Steps:

  1. Place coin on table.
  2. Place empty glass over coin. Can see coin.
  3. Pour water into glass. Coin seems to disappear.

Learning: Refraction changes apparent position.

6. Magnifying Water Droplet (Ages 5+)

Materials: Waxed paper, small water droplet Steps:

  1. Place waxed paper over text.
  2. Put droplet on top.
  3. Text appears larger through droplet.

Learning: Water droplet acts as magnifying lens.

Prism + Dispersion (2)

7. Prism Rainbow (Ages 4+)

Materials: Prism ($5), sunny window Steps:

  1. Hold prism in sunlight.
  2. Rainbow appears on surface.
  3. Rotate to see different angles.

Learning: White light is made of all colors.

8. Water Prism (Ages 5+)

Materials: Clear glass of water, white paper, sunny window Steps:

  1. Place glass near window in sun.
  2. Paper on other side.
  3. Rainbow may form on paper.

Learning: Water can act as prism (briefly).

Color Mixing (3)

9. Color Mixing with Food Coloring (Ages 4+)

Materials: Clear cups, water, food coloring Steps:

  1. Red + blue = purple.
  2. Red + yellow = orange.
  3. Yellow + blue = green.
  4. All three = brown.

Learning: Primary color mixing (subtractive).

10. Color Filter Addition (Ages 6+)

Materials: Colored cellophane (red, blue, green), flashlight Steps:

  1. Shine flashlight through red cellophane = red light.
  2. Red + blue cellophane overlap = darker.
  3. Add green = even darker.

Learning: Cellophane filters subtract colors from white light.

11. RGB Mixing with Light (Ages 8+)

Materials: Red, green, blue LED flashlights OR colored gels over flashlights Steps:

  1. Red + green = yellow.
  2. Red + blue = magenta.
  3. All three = white.

Learning: Light-based color mixing is additive (differs from paint which is subtractive).

Shadow Experiments (2)

12. Shadow Tracking Over Day (Ages 4+)

Materials: Chalk, stick, sunny day Steps:

  1. Stand stick in ground at 9 AM.
  2. Trace shadow with chalk.
  3. Retrace every hour.
  4. Shadow rotates as sun moves.

Learning: Earth’s rotation causes shadow movement.

13. Shadow Depth (Ages 5+)

Materials: Objects of different transparency Steps:

  1. Hold object in sunlight.
  2. Solid object = full shadow.
  3. Translucent = partial shadow.
  4. Transparent = no shadow.

Learning: Opacity degrees.

Advanced (2)

14. Pinhole Camera (Ages 10+)

Materials: Cardboard box, wax paper, pin Steps:

  1. Dark room setup.
  2. Tiny pinhole on one side; wax paper on opposite.
  3. Bright scene through pinhole creates inverted image on wax paper.

Learning: Light travels in straight lines; pinhole creates image.

15. Polarization with Two Lenses (Ages 12+)

Materials: Two polarizing filters (from sunglasses or science store) Steps:

  1. Look through both aligned.
  2. Rotate one 90°.
  3. Light blocks out.

Learning: Polarization; light as wave.

Science Fair Extensions

  • Reflection angles: Measure angle-in vs angle-out with mirror.
  • Refraction index: Different liquids (water, oil, glycerol) with object.
  • Color perception: Which background colors make objects seem which colors?

See our science fair project guides.

Pairing With Equipment

  • Magnifying glass: For detail work.
  • Small mirrors: For reflection work.
  • Prism: Essential for dispersion.
  • Flashlight: For controlled-dark experiments.
  • Dark room: Closet works.

Common Classroom Pairings

Light unit as part of physical science:

  • Weeks 1–2: Reflection
  • Week 3: Refraction
  • Week 4: Dispersion + color
  • Weeks 5–6: Shadows + sun path

The Bottom Line

Starter set: Prism ($5) + small mirrors ($10) + flashlight + food coloring. Under $20.

Most engaging experiments:

  • Prism rainbow (ages 4+)
  • Pencil in water (ages 4+)
  • Color mixing (ages 4+)
  • Mirror reflection (ages 5+)

Best classroom unit: 3–4 weeks of light + color activities.

Light experiments teach real physics that kids see every day. Foundational for upper-elementary science.

All experiments tested with kids 4–12.