Grade by Grade
C. Matter and Energy · Properties of and Changes in Matter

Materials and the Environment: Making Better Choices

C1.2 A1.1 A3.2 A1.5About 45 minutes
Learning goals
  • I can assess how using certain materials in products affects the environment.
  • I can compare materials like plastic, glass, aluminium and paper.
  • I can identify actions that individuals and society can take to reduce harm to the environment.

Words to know

single-use
Made to be used once and then thrown away, like a plastic straw.
recycle
To collect used materials and process them into new products.
reuse
To use something again, for the same job or a new one.
biodegradable
Able to be broken down by living things, like bacteria and fungi, into natural substances.
mitigate
To make a harmful effect smaller or less serious.
landfill
A place where garbage is buried in the ground.

What happens to your juice box?

You finish a juice box at lunch and toss it. Where does it go? A juice box is made of layers of paper, plastic and aluminium glued together. That makes it hard to recycle in many places. The materials chosen for a product affect the environment long after you use it.

Comparing common materials

Plastic (made from oil and natural gas)

  • ✔ light, waterproof, cheap, can be shaped into anything
  • ✘ most plastics are not biodegradable: they can last for hundreds of years
  • ✘ plastic litter can harm animals that get tangled in it or eat it, and it breaks into tiny pieces called microplastics
  • ✘ only some kinds are recycled in many communities

Glass (made from sand)

  • ✔ can be recycled over and over
  • ✔ easy to wash and reuse
  • ✘ heavy (more fuel to ship) and breaks; melting it takes a lot of energy

Aluminium (made from a rock ore called bauxite)

  • ✘ getting the ore and making new aluminium takes a lot of energy
  • ✔ recycling aluminium cans takes much less energy than making new aluminium, and cans can be recycled again and again

Paper and cardboard (made from trees)

  • ✔ comes from a renewable resource if forests are replanted and cared for
  • ✔ biodegradable and widely recycled
  • ✘ cutting forests destroys habitats; paper fibres get shorter each time they are recycled, so paper can't be recycled forever

Four questions

No material is perfect. To assess a material, ask: Where does it come from? How much energy does it take to make? How long will it be used? What happens to it afterward?

Actions individuals can take

  • Reduce: buy less, choose products with less packaging, say no to things you don't need (like extra straws).
  • Reuse: refill a water bottle, use lunch containers instead of plastic bags, give clothes and toys to others.
  • Repair: fix a broken zipper or a bike instead of replacing it.
  • Recycle correctly: rinse containers and follow your community's blue box rules (they are different in different places).
  • Compost food scraps (in a green bin or backyard composter, if your community has one).
  • Choose products made from recycled materials.
A blue recycling bin at the end of a driveway filled with plastic bottles, glass jars, cans and flattened cardboard.
Rinsed bottles, jars, cans and cardboard can go in the blue box, but the rules are different in different communities, so check what yours accepts. AI-generated image
REDUCEbuy less, less packagingREUSE and REPAIRrefill, fix, give awayRECYCLE and COMPOSTfollow local rulesLANDFILLlast choicebestfirst
Start at the top: reducing and reusing save the most. Recycling and composting come next, and the landfill is the last choice.

Actions society can take

  • Laws and rules, such as limits on some single-use plastic items.
  • Deposit-return programs: you pay a small deposit on some drink containers and get it back when you return them. In Ontario, wine, beer and spirits containers can be returned this way.
  • Companies can design products that are easier to recycle, use less packaging, or take back their old products.
  • Communities can run recycling, composting and hazardous-waste collection programs.

Thinking about the future

Many First Nations, Métis and Inuit teachings encourage people to take only what they need, use everything carefully, and think about how today's choices will affect the land and future generations. Many Haudenosaunee people, for example, speak of considering the effects of decisions on the seventh generation to come. This way of thinking is a helpful guide for choosing materials.

Worked example

Let's assess three lunch drink containers

Which is the best choice for the environment: a single-use plastic water bottle, a juice box, or a reusable steel bottle?

  1. Plastic bottle: made from oil; used once; can often be recycled, but many end up as litter or in landfills ✘.
  2. Juice box: layers of paper, plastic and aluminium glued together; used once; hard to recycle in many places ✘.
  3. Steel bottle: takes more energy and materials to make at first ✘, but it can be reused for years ✔✔. After a school year of daily use, it has replaced well over a hundred single-use containers.
  4. Judgment: the reusable steel bottle, as long as it is used for a long time.

The reusable bottle is the best choice because it is used over and over. Reduce and reuse come before recycle.

1 reusable bottlereplaces100 single-use containers... and more!
One reusable bottle, used every school day for a year, replaces well over a hundred single-use containers.
Just for fun

Why is a glass jar never worried about retiring?

Glass can be recycled over and over, so it always comes back for another job!

Hands-on activity

One-day waste audit

You need: rubber gloves, a large sheet of paper or a tarp, a grown-up, a notebook, and one day of your household's garbage, recycling and food scraps.

  1. Research first: with a grown-up, look up your community's recycling and green-bin rules online.
  2. Wearing gloves, help a grown-up sort one day's waste into groups by material: plastic, glass, metal, paper/cardboard, food scraps, other.
  3. Count the items in each group. Record them in a table.
  4. Math connection: make a bar graph of your results.
  5. Which material did your family throw out the most? Which items could have been reduced, reused, recycled or composted instead?
  6. Make a plan: write 3 actions your family can try for one week. Present your graph and plan to your family.

What to look for: a table and graph by material, and actions that match the materials found (for example: "Use a reusable container instead of plastic bags for sandwiches").

Safety: always wear gloves. A grown-up handles anything sharp (broken glass, can lids), anything from the bathroom, and any product containers with safety symbols. Wash your hands afterward.

Your turn

1

What raw material is plastic made from?

2

Name one problem with plastic in the environment.

3

Why is recycling aluminium cans a good idea?

4

Name three actions you can take to reduce the impact of materials.

5

Why is a juice box hard to recycle?

6

Give one action that society (not just one person) can take.

More practice: warm-up

1

Is paper biodegradable?

2

Which can be recycled over and over: glass or a juice box?

3

Which comes first: reduce or recycle?

4

What does single-use mean?

5

Where does garbage go if it isn't recycled or composted?

More practice: on your own

1

Glass can be recycled over and over. Name one disadvantage of glass.

2

Why is reusing better than recycling, when you can?

3

How does a deposit-return program encourage people to recycle?

4

Paper is made from a renewable resource. What must happen for it to stay renewable?

5

Describe the idea of thinking about the seventh generation.

Challenge

1

A store switches from plastic bags to paper bags. Assess this change. Is it all good?

2

Design a waste-free lunch. List each item and its container.

3

Your school throws out many single-use plastic water bottles. Write a short plan to mitigate this, with two actions by students and one by the school.

Check your understanding

Quiz

1.

Most plastics are made from...

2.

Which material can be recycled over and over?

3.

Recycling aluminium cans saves energy because...

4.

Which action is reusing?

5.

To mitigate a negative impact means to...

6.

Which is an action by society rather than one person?

For parents and teachers

Big idea: Ontario Grade 5 expectation C1.2 asks children to assess how the use of specific materials in the manufacture of common products affects the environment, and to identify actions that society and individuals can take to mitigate negative impacts. The waste audit uses research (A1.1), a connection to math graphing (A3.2), and presenting a plan (A1.5).

How to help: Do the waste audit together and follow through on the family plan for a week. Check your local blue box and green bin rules together; they differ across Ontario.

Common difficulties:

  • Thinking recycling solves everything. Reduce and reuse come first.
  • Thinking one material is always "good" and another always "bad". Encourage weighing trade-offs.
  • Ideas without action. Ask "What will you do this week?"

When discussing Indigenous teachings, present them as living knowledge held by many different nations, not one single view.

Safety: you handle sharp items, bathroom waste and anything with a hazard symbol. Gloves and handwashing for everyone.