C. Matter and Energy · Light and Sound

Light and Sound in the Environment: Light Pollution and Noise

C1.2 A1.1 A3.2About 40 minutes

Learning goals

I can describe how artificial light at night affects animals, people and the night sky.
I can describe how noise from technologies affects animals and people.
I can describe ways to reduce light pollution and noise pollution.
I can look at an issue from different perspectives.
I can follow a research process to answer a question.

Words to know

environment
Everything around us: land, water, air, plants, animals and people.

light pollution
Too much artificial light at night, or light shining where it is not needed.

noise pollution
Loud or constant sounds made by people's machines that harm or bother people or animals.

migrate
To travel a long way at the same time each year, like birds flying south in fall.

perspective
A person's point of view: how they see an issue.

dark-sky preserve
A place where outdoor lights are kept low so people can see the stars.

Where did the stars go?

On a clear night in a big city, you might see only a few stars. Far out in the country, you can see thousands, and maybe the cloudy band of the Milky Way. The stars are still there over the city. They are hidden by all the artificial light shining up into the sky.

Light and sound are useful forms of energy. But when technologies give off too much light or sound in the wrong places, they can harm the environment.

The Milky Way and thousands of stars shine over a dark lake and forest far from any city. — Far from city lights, the sky is dark enough to see the Milky Way. Light pollution hides this view in cities. AI-generated image

Same sky, same stars. In the city, artificial light shining up into the sky hides most of them. Far from city lights, you can see many more.

Light pollution

Light pollution is too much artificial light at night, or light shining where it is not needed, such as up into the sky.

It can affect:

Birds: many songbirds migrate at night. Bright lights from tall buildings can confuse them, and some fly into windows. Some cities ask building owners to turn off lights at night during migration seasons.
Insects: moths and other insects circle around lights all night instead of feeding or finding mates. Then fewer insects are left for birds and bats to eat.
People: bright lights shining in bedroom windows can make it harder to sleep.
The night sky: light pollution hides the stars. Many First Nations, Métis and Inuit communities have star knowledge passed down for generations, used for stories, travel and knowing the seasons. Dark skies help keep that knowledge alive for everyone to learn from.
Energy: lights left on when no one needs them waste electricity.

Noise pollution

Noise pollution is loud or constant sound from people's machines: traffic, airplanes, construction, snowmobiles, leaf blowers, ships.

It can affect:

Whales: whales like belugas use sound to find each other and find food, and they hear sound travelling far through water. Noise from ships' engines can make it harder for them to hear.
Birds and other animals: many animals use sound to find mates, warn of danger or hear predators. Noise can drown out their calls.
People: constant noise can make it hard to sleep, concentrate or talk, and very loud noise can damage hearing.

Solutions

For light pollution:

Use shielded outdoor lights that point down, not up or sideways.
Use motion sensors and timers so lights are on only when needed.
Turn off lights in empty rooms and buildings, and close curtains at night.
Use dimmer, warmer-looking lights outdoors.
Protect dark-sky preserves. Canada has several places where lights are kept low so people can see the stars.

For noise pollution:

Quieter machines and electric vehicles.
Noise walls, trees and hedges between roads and homes.
Rules about quiet hours at night.
Ships slowing down in some places where whales live, which makes them quieter.

A shielded light sends its light down where people need it. An unshielded light sends some light up into the sky, adding to light pollution.

Different perspectives

People often see the same issue differently. Think about bright lights at a new park:

A parent may like them because the park feels safer after dark.
A neighbour may dislike light shining into their bedroom.
A birdwatcher may worry about birds and insects.
An astronomy club member may want to see the stars.
The town council must think about safety, cost and the environment all together.

A good decision listens to all these voices and looks for a solution that works for many of them.

Just for fun

Moths can circle a porch light all night long, like guests at a party that never ends. Switch the light off, and they can finally get back to their real job: being snacks for bats and birds!

Worked example

Let's research a question

Question: How can our town light a new park safely without harming birds and insects? Follow a research process.

1. Ask a clear question. (Done above.)
2. Find information from reliable sources: a library book, a government or science centre website, or an expert like a park worker. Write down where each fact came from.
3. Take notes in your own words: shielded lights that point down keep light off the sky; motion sensors keep lights off when nobody is there; lights can be turned off late at night.
4. Think about perspectives: families want safety; neighbours want dark bedrooms; nature lovers want to protect wildlife.
5. Conclude: use shielded, downward-pointing lights on motion sensors along the paths, and turn them off after the park closes.
6. Communicate: make a poster or a short letter to the town council with your idea and your reasons.

A research process: question → reliable sources → notes → perspectives → conclusion → share. The solution keeps the park safe while reducing light pollution.

Hands-on activity

Light and noise detective

You need: paper, a pencil, a clipboard or a hard book, and a grown-up for the night walk.

Part 1: Light audit (evening). With a grown-up, walk around your home and street after dark. Make a tally chart of outdoor lights: points down or shines up or sideways, and needed or not needed. Which lights could be changed?

Part 2: Star count. On a clear night, look through a tube from a paper towel roll at the same part of the sky. Count the stars you can see. If you can, compare with a darker place (a park away from lights, or the cottage). More stars = less light pollution.

Part 3: Noise map. Sit quietly for 5 minutes outside in two places (for example, the front yard by the road and the back yard). Tally every sound: nature sounds (birds, wind) and machine sounds (cars, mowers). Make a bar graph comparing the two places.

Part 4: Take action. Pick one idea to reduce light or noise at home (turn off the porch light at bedtime, close curtains, lower the TV volume) and try it for a week.

What to look for: a tally chart that sorts lights, a star count, a bar graph with clear labels, and one action. Children often notice the front yard is noisier and that some lights shine upward for no reason.

Safety: a grown-up comes on the night walk. Stay on the sidewalk, wear reflective clothing, and never look at the Sun during the day parts.

Your turn

What is light pollution?

How can bright city lights harm migrating birds?

Why can you see more stars in the country than in a city?

How can ship noise affect whales?

Name two ways to reduce light pollution.

Name two ways to reduce noise pollution.

More practice: warm-up

Is a streetlight natural or artificial light?

Name one machine that makes noise pollution.

What does migrate mean?

What is a dark-sky preserve?

What is a perspective?

More practice: on your own

Why does a shielded light that points down cause less light pollution?

Moths circle a porch light all night. How might this affect other animals?

Why might a neighbour and a store owner have different perspectives about a bright store sign?

In Part 3, Sam counted 14 machine sounds in the front yard and 5 in the back yard. How many more in the front? Why might that be?

Why are dark skies important to many First Nations, Métis and Inuit communities?

Challenge

Your school wants to leave its outdoor lights on all night for safety. Suggest a plan that keeps safety but reduces light pollution and wasted energy.

Give two perspectives on adding a busy new highway near a wetland, one for and one against, with reasons.

Plan the research steps you would follow to answer: "Does noise from our street change how many birds we hear?"

Check your understanding

Quiz

Light pollution is...

Which outdoor light causes the least light pollution?

How can bright lights harm migrating birds?

Which animals can have trouble hearing each other because of ship noise?

Which is a way to reduce noise pollution near a highway?

A perspective is...

For parents and teachers

Big idea: Ontario Grade 4 expectation C1.2 asks children to assess the impacts on the environment of light energy and sound energy produced by various technologies, taking different perspectives into account. Light pollution and noise pollution are the main examples. The research example follows a scientific research process (A1.1), and tallies and bar graphs connect to math (A3.2).

How to help: Go on the evening light walk and star count together; it's a memorable family outing. If you visit a cottage or campground, compare the stars with home. Talk about your own outdoor lights and whether they could point down or go on a timer.

Common difficulties:

Thinking all lights are bad. The goal is the right light in the right place at the right time.
Only seeing one side. Ask "Who would want this? Who might not? Why?"
Indigenous perspectives: present First Nations, Métis and Inuit star knowledge as living knowledge held by many communities today. Each community has its own knowledge and stories; avoid treating them as one group.

Safety: supervise night walks; use reflective clothing and stay on sidewalks.