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

Light Is Energy: Natural and Artificial Light Sources

C2.1 A1.5About 30 minutes
Learning goals
  • I can explain that light is a form of energy.
  • I can explain what a light source is.
  • I can name natural light sources and artificial light sources.
  • I can sort light sources and show my sorting in a chart.
  • I can follow the safety rule: never look at the Sun or into a laser.

Words to know

energy
What makes things happen: makes things move, light up, warm up or make a sound.
light
A form of energy that lets us see.
light source
Something that gives off (makes) its own light, like the Sun or a flashlight.
emit
To give off or send out. A light bulb emits light.
natural
Made by nature, not by people.
artificial
Made by people.
bioluminescence
Light made by a living thing, like a firefly.

Lights out!

It is a snowy evening in January. The Sun went down early, at about five o'clock. Suddenly, the power goes out. The lamps go dark. The TV goes black. Your house is very dark.

What could you use to see? A flashlight? A phone screen? Maybe the Moon shining on the snow outside?

In this unit you will learn all about light and sound: where they come from, how they travel, and how we use them.

Remember from Grade 1

In Grade 1 you learned that the Sun is Earth's most important source of energy. It gives us light and heat. Now we will look much more closely at light.

Light is energy

Energy is what makes things happen. It makes things move, warm up, light up or make a sound.

Light is a form of energy. Light lets us see. Plants use the energy in sunlight to grow. Some calculators and garden lamps run on sunlight.

A light source is something that gives off its own light. Scientists say it emits light. The Sun is a light source. A lamp that is turned on is a light source.

Natural and artificial light sources

Light sources come in two groups.

Natural light sources are made by nature, not by people:

  • the Sun, which is a star
  • the other stars in the night sky
  • lightning in a thunderstorm
  • the northern lights (aurora borealis), which dance across the sky in northern Canada
  • living things that make their own light, like fireflies and some deep-sea fish and jellyfish. Light made by a living thing is called bioluminescence.

Artificial light sources are made by people:

  • light bulbs and lamps
  • flashlights
  • TV, computer, tablet and phone screens
  • traffic lights and car headlights
  • candles
  • glow sticks
  • lighthouses
Green northern lights swirl across a starry night sky above a snowy forest and frozen lake.
The northern lights and the stars are natural light sources: they give off their own light, with no help from people. AI-generated image
☀️⭐⚡💡🔦🕯️🚦
Seven light sources: the Sun, a star, lightning, a light bulb, a flashlight, a candle and a traffic light. The first three are natural. The last four are artificial.
Does it give off its own light?yesnoa LIGHT SOURCENOT a light source(Moon, mirror, book)Who made it?naturepeopleNATURALSun, star,fireflyARTIFICIALlamp, screen,candleI made my own!
Ask two questions to sort anything you see. First: does it give off its own light? If yes, ask: did nature or people make it?
Natural light sources (made by nature)Artificial light sources (made by people)
Sunlight bulb
starsflashlight
lightningphone or tablet screen
northern lightscandle
fireflycar headlights
A T-chart sorts light sources into two groups.

Safety: protect your eyes

  • Never look straight at the Sun, not even with sunglasses, and not through binoculars, a telescope or a magnifying glass. Sunlight is so strong that it can damage your eyes forever.
  • Never look into a laser pointer, and never shine one at a person, a pet, a car or an airplane.
  • Do not shine a flashlight into anyone's eyes.
  • Candles are only lit by a grown-up.
Worked example

Let's sort some light sources

Sort these into natural and artificial light sources: the Sun, a flashlight, a firefly, a ceiling light, lightning, a tablet screen.

  1. Ask the question for each one: Did people make it, or did nature make it?
  2. The Sun: nobody made the Sun. It is a star. → natural.
  3. A flashlight: people build flashlights in factories. → artificial.
  4. A firefly: a firefly is an insect that makes its own light (bioluminescence). → natural.
  5. A ceiling light: made by people and wired into a house. → artificial.
  6. Lightning: made by nature during a storm. → natural.
  7. A tablet screen: made by people. → artificial.

Natural: the Sun, a firefly, lightning. Artificial: a flashlight, a ceiling light, a tablet screen.

Science talk: share what you found

Scientists communicate their results so other people can understand them. A T-chart with two clear headings is a great way to share a sort. Use science words like light source, emit, natural and artificial.

A tricky one: the Moon

The Moon shines brightly at night. But is it a light source? Think about it. You will find out the answer in the next lesson!

Just for fun

Riddle: What can fill a whole room but takes up no space at all?

Light!

Hands-on activity

Light source hunt

You need: paper, a pencil and a ruler.

  1. Draw a T-chart. Label one side Natural and the other side Artificial.
  2. Walk through your home with a grown-up. Look for things that give off their own light when they are on: lamps, the stove clock, a night light, screens, the light inside the fridge, a smoke alarm's little light.
  3. Write each one in your chart.
  4. Look out a window. Can you see any natural light sources? (Remember: do not look straight at the Sun.)
  5. Count how many you found on each side. Which side has more? Why do you think so?
  6. Share: explain your chart to a family member using the words light source, natural and artificial.

What to look for: most things inside a home are artificial light sources. Natural ones are usually outside (the Sun, stars, lightning). Your child should only list things that make their own light, not shiny things that just look bright.

Safety: don't touch light bulbs (they can be hot), and leave candles to grown-ups.

Your turn

1

What is a light source?

2

Is light a form of energy?

3

Is a firefly a natural or an artificial light source?

4

Is a traffic light a natural or an artificial light source?

5

Name two natural light sources.

6

Name two artificial light sources in your home.

7

What is the closest star to Earth?

More practice: warm-up

1

Natural or artificial: lightning?

2

Natural or artificial: a car headlight?

3

Natural or artificial: a star?

4

Natural or artificial: a glow stick?

5

What does the word emit mean?

More practice: on your own

1

Why is a candle an artificial light source, even though the flame is fire?

2

Why should you never look at the Sun through binoculars?

3

A lamp is turned off. Is it a light source right now? Explain.

4

Name a light source that is also a living thing. What is this kind of light called?

5

Explain how plants show that light is energy.

Challenge

1

Ben's T-chart lists mirror under artificial light sources. Is he right? Explain.

2

People in the past used only natural light during the day. Name two artificial light sources that let people today work and play after dark, and say how each one helps.

3

In northern Canada, the northern lights can fill the sky with moving light. Are they natural or artificial, and how do you know?

Check your understanding

Quiz

1.

Which is a natural light source?

2.

Which is an artificial light source?

3.

What is the Sun?

4.

Light is a form of...

5.

Which of these should you never do?

6.

A light source is something that...

For parents and teachers

Big idea: Ontario Grade 4 expectation C2.1 asks children to identify a variety of natural and artificial light sources. Light is introduced as a form of energy. Sorting into a T-chart and explaining it practises communicating results (A1.5).

How to help: On a walk or drive after dark, play "natural or artificial?" with every light you see. Ask "Who made it, people or nature?"

Common difficulties:

  • Listing shiny or bright things (mirrors, snow, the Moon, a reflector) as light sources. These only bounce light. That is the focus of the next lesson.
  • Thinking all light sources are hot. Fireflies and glow sticks give light with very little heat (lesson 6).
  • Fire and candles: a candle is usually called artificial because people make and light it. Lightning is natural. Don't worry about edge cases like campfires; focus on the question "made by people or by nature?"

Safety: repeat the eye rules often: never look at the Sun (even with sunglasses or through binoculars), never look into a laser pointer, and candles are for grown-ups only.