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Reduce, reuse, recycle

Sort wet and dry waste into the right bins, learn the three Rs and discover how kitchen waste can turn into compost for plants.

Get the whole book: Science for classes 3 to 5 (9 lessons, free to print)

Let us begin

The big idea

Every home makes waste every day: peels, wrappers, paper, bottles. Where does it all go? In this lesson you will learn to sort waste, to make less of it and to turn some of it into something useful.

Waste that rots and mixes back into the soil is called biodegradable waste: fruit and vegetable peels, leftover food, leaves, paper and cotton cloth. Waste that does not rot for a very long time is non-biodegradable: plastic bags, bottles, glass, metal cans and batteries.

Sorting waste at home makes it easy to deal with. Wet waste such as peels and food goes in the green bin. Dry waste such as paper, plastic, glass and metal goes in the blue bin. Harmful waste such as batteries, medicines and broken tubes should be kept separate and handed to the right collection point.

The three Rs tell us what to do. Reduce: make less waste by carrying a cloth bag and a steel bottle instead of buying plastic. Reuse: use things again, like turning a jam jar into a pencil holder or writing on the back of used paper. Recycle: send paper, plastic, glass and metal to be made into new things.

Wet waste can be turned into compost. In a pot or pit, layers of peels and dry leaves slowly rot with the help of tiny living things and earthworms. After some weeks it becomes dark, crumbly manure that makes plants grow well.

Throwing waste on roads, in drains or in rivers makes places dirty, blocks drains, spreads disease and harms animals that eat plastic by mistake. A clean neighbourhood starts with sorted waste at home.

Waste sorting binsThree dustbins side by side. The green bin is labelled wet waste with peels, food and leaves listed under it. The blue bin is labelled dry waste with paper, plastic, glass and metal listed. A smaller red bin is labelled harmful waste with batteries and medicines. Above the bins the three Rs are written: reduce, reuse, recycle.Reduce, reuse, recycle, and sort what is left GREEN Wet waste peels, leftover food leaves, egg shells rots into compost BLUE Dry waste paper, plastic glass, metal cans can be recycled RED Harmful batteries, medicines broken tubes special collection
Green for wet waste, blue for dry waste, and a separate bin for harmful things.

Worked examples

See how it works

  1. Sorting a day of waste

    A family throws away banana peels, a milk packet, a newspaper, an egg shell and a glass bottle. Peels and egg shell are wet waste: green bin. Milk packet, newspaper and bottle are dry waste: blue bin. The newspaper, packet and bottle can all be recycled.

  2. Choosing to reduce

    Rahul buys a packet of chips every day at school. That is five wrappers a week and about 200 in a year. If he carries roasted chana in a steel box instead, he makes zero wrappers. Reducing stops waste before it is made.

  3. Reuse before you throw

    An old T-shirt can become a cleaning cloth or a shopping bag. A plastic ice-cream box can store buttons. A cardboard box can become a toy house. Each reuse keeps one thing out of the dustbin.

Try it at home

Compost in a pot

You will need

  • An old bucket, pot or large plastic container with a few holes in the bottom
  • Fruit and vegetable peels
  • Dry leaves or torn newspaper
  • A little soil
  • A stick for mixing

What to do

  1. Put a layer of soil at the bottom of the container.
  2. Add a layer of peels, then a layer of dry leaves or torn paper. Repeat each day with new peels.
  3. Keep it slightly damp, not wet, and cover it with a cloth or lid.
  4. Mix it with the stick once a week. It should smell like wet earth, not rotten.
  5. After about six to eight weeks, the dark crumbly compost at the bottom is ready to feed a plant.

Ask a grown-up: Ask an adult to make the holes in the container, and keep the compost pot outside the kitchen.

Practice sheet

Check what you learned

Write your answers in a notebook, or print this sheet and write on it. When you finish, mark your work with the answer key.

Practice sheet: Reduce, reuse, recycle (Classes 3-5, Science)

  1. What is biodegradable waste? Give two examples.
  2. Name two kinds of non-biodegradable waste.
  3. Which bin does wet waste go into?
  4. Which bin do paper and plastic go into?
  5. What are the three Rs?
  6. Give one example of reducing waste.
  7. Give one example of reusing something.
  8. What is compost?
  9. Where should old batteries go?
  10. Why is throwing plastic into a river harmful?

Answer key

Answers: Reduce, reuse, recycle

Do the practice sheet first, then check here. If an answer is different from yours, read the lesson again and try once more.

  1. Waste that rots and mixes back into the soil, such as peels, leftover food, leaves or paper.
  2. Any two: plastic bags, plastic bottles, glass, metal cans, batteries.
  3. The green bin.
  4. The blue bin (dry waste).
  5. Reduce, reuse, recycle.
  6. For example, carrying a cloth bag or a steel bottle instead of buying plastic ones.
  7. For example, using a jam jar as a pencil holder or writing on the back of used paper.
  8. Dark, crumbly manure made when wet waste rots; it helps plants grow.
  9. In a separate bin for harmful waste, to be handed to a special collection point.
  10. It makes the water dirty, blocks the flow and harms animals that may eat it.

What next

Keep learning

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All 9 science lessons for classes 3 to 5 on one page, with every practice sheet and answer key, ready to print.

Science for classes 3 to 5

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