Grade by Grade
C. Matter and Energy · Light and Sound

Light and Sound: Unit Review

A1.1 A1.2 A1.3 A1.4 A1.5 A2.1 A2.2 A3.1 A3.2 A3.3 C1.1 C1.2 C2.1 C2.2 C2.3 C2.4 C2.5 C2.6 C2.7 C2.8About 40 minutes
Learning goals
  • I can describe light sources and the properties of light: it travels in straight lines and can be reflected, absorbed and refracted.
  • I can explain how vibrations make sound, and how sound travels, echoes, is absorbed and is changed.
  • I can identify sensory organs and devices that use light and sound.
  • I can assess the impacts of light and sound technologies on society and the environment.

Words to know

light source
Something that emits its own light.
reflect
To bounce off a surface.
refraction
The bending of light when it passes from one material into another.
vibration
A quick back-and-forth movement that makes sound.
pitch
How high or low a sound is.
medium
The material sound travels through: a gas, a liquid or a solid.
light pollution
Too much artificial light at night.

Let's review!

In this unit you became an expert on two forms of energy: light and sound. You sorted natural and artificial light sources, found out what emits light and what only reflects it, proved that light travels in straight lines, and explored reflection, absorption and refraction. You compared hot and cool light, discovered that vibrations make sound, learned how sound travels, echoes and is absorbed, studied your eyes and ears and many devices, and assessed how light and sound technologies affect people and the environment.

This review has a few questions from every lesson. Try each one, then press Show answer to check. If a part feels tricky, go back to that lesson.

lightREFLECTbounces offmirrorABSORBsoaks in, warms upblack shirtPASS THROUGHtransparent ortranslucentREFRACTbends at a boundarystraw in water
A quick map of what light can do when it meets something: reflect, be absorbed, pass through, or refract (bend).
VIBRATIONsomething movesback and forthMEDIUMair, wateror a solidEAReardrumvibratesBRAINyou hearthe sound!fast vibrations = high pitchbig vibrations = loudno medium (outer space) = no sound
The journey of every sound, from a vibration through a medium to your ear and brain.

Light Is Energy: Natural and Artificial Light Sources

1

Natural or artificial: a firefly? A street light?

2

What is a light source?

3

Name the rule about the Sun and your eyes.

Making Light or Bouncing It: Emit or Reflect?

1

Does the Moon emit light or reflect it?

2

How do you see a non-luminous object like a chair?

3

Why can't you see a bike reflector in a totally dark room?

Light Travels in Straight Lines: Shadows and Materials

1

Give one piece of evidence that light travels in straight lines.

2

Transparent, translucent or opaque: wax paper? Cardboard? Clear plastic wrap?

3

How can you make a shadow bigger?

Light Bounces and Soaks In: Reflection and Absorption

1

Why can you see your image in a mirror but not in a towel?

2

Which warms up more in the Sun, a black mitten or a white one? Why?

3

How do Inuit snow goggles protect the eyes?

Bending Light: Refraction, Lenses and Rainbows

1

What is refraction?

2

Why does a straw look broken in a glass of water?

3

Why must you never aim a magnifying glass at sunlight onto paper?

Hot Light and Cool Light: Light Sources and Heat

1

Sort: candle, LED bulb, Sun, glow stick. Which give a lot of heat?

2

Why do LED bulbs save energy?

3

What two things did the Inuit qulliq give a home?

Vibrations Make Sound: Pitch and Loudness

1

What makes every sound?

2

Which makes a higher pitch, a long thick string or a short thin string? Why?

3

You hit a drum harder. What changes, pitch or loudness?

4

Name one way to protect your hearing.

How Sound Travels: Echoes, Absorbing and Changing Sound

1

Why is outer space silent?

2

You count 15 seconds between lightning and thunder. About how far away is the storm?

3

Does fresh snow reflect or absorb sound? What about a gym wall?

Our Eyes, Our Ears, and Devices That Use Light and Sound

1

Name the part of the eye that bends light and the part of the ear that vibrates first.

2

Light or sound: a hearing aid? A periscope? Sonar?

3

Code: "if brightness < 30 then turn lamp ON, else turn lamp OFF". Brightness is 45. On or off?

Light and Sound Devices: How They Affect Our Lives

1

Give one benefit and one drawback of smartphones.

2

How do flashing fire alarms make a building more accessible?

3

What should a good assessment of a device include?

Light and Sound in the Environment: Light Pollution and Noise

1

Name one way light pollution affects animals.

2

Name one way to reduce noise pollution.

3

Why might two people disagree about a bright new sign in a neighbourhood?

Just for fun

Light and sound had a race. Light won by a mile... actually by a LOT of miles! Light travels about 300 000 km every second, while sound covers only about 340 m. Sound is still catching its breath.

How to use this review

  • Do the review in two short sittings if your child gets tired: light (first six sections) and sound plus impacts (last five).
  • Keep a flashlight, a mirror, a glass of water with a straw and a rubber band nearby so your child can show answers.
  • Ask "How do you know?" Good answers use the science words: emit, reflect, absorb, refract, vibrate, pitch, medium.
  • Note which section had mistakes and redo that lesson's activity.
Check your understanding

Quiz

1.

Which is an artificial light source?

2.

The Moon...

3.

A shadow forms because...

4.

A pencil in water looks broken because of...

5.

Which material is translucent?

6.

Which light source gives off light with little heat?

7.

A short, thin, tight string makes a sound that is...

8.

An echo is sound that is...

9.

Bats use echolocation, which means they...

10.

Which action best reduces light pollution?

For parents and teachers

Use mistakes to choose what to revisit. Each review section matches one lesson.

  • Calls mirrors or the Moon light sources, or mixes up natural and artificial: revisit Light Is Energy: Natural and Artificial Light Sources and Making Light or Bouncing It: Emit or Reflect?, and redo the dark-room test.
  • Can't explain shadows, or mixes up transparent and translucent: revisit Light Travels in Straight Lines: Shadows and Materials and redo the shadow lab.
  • Thinks only mirrors reflect, or that dark colours "attract" heat: revisit Light Bounces and Soaks In: Reflection and Absorption.
  • Mixes up reflection and refraction, or can't explain the broken straw or rainbows: revisit Bending Light: Refraction, Lenses and Rainbows and redo the coin trick.
  • Thinks all light sources are hot, or can't explain why LEDs save energy: revisit Hot Light and Cool Light: Light Sources and Heat.
  • Confuses pitch with loudness: revisit Vibrations Make Sound: Pitch and Loudness and play the rubber-band guitar.
  • Thinks sound travels in space, or mixes up reflect and absorb for sound: revisit How Sound Travels: Echoes, Absorbing and Changing Sound.
  • Mixes up eye and ear parts, can't match devices to light or sound, or reads < and > backwards: revisit Our Eyes, Our Ears, and Devices That Use Light and Sound and play the unplugged night-light game.
  • Lists only good or only bad impacts of a device, or gives opinions without reasons: revisit Light and Sound Devices: How They Affect Our Lives.
  • Thinks all lights are bad, or sees only one perspective: revisit Light and Sound in the Environment: Light Pollution and Noise and do the evening light walk.

A few mistakes are normal. Praise your child for using the science words and explaining how they know.