Science Experiments With Recycled Materials for Kids

You do not need to buy anything to do good science with a child. The recycling bin is full of useful equipment, and using it shows children something worth knowing: scientists improvise, and a good question matters more than fancy materials.

Before you start, a few safety habits. Wash and dry every container. Adults do all the cutting, and cut edges on plastic bottles should be smoothed with a strip of tape. Skip anything that held chemicals, and skip glass that is chipped or cracked.

Start with a “bin audit”

Tip the clean recycling onto a mat and sort it together: paper, card, plastic, metal, glass. Ask: “Which of these is bendy? Which is waterproof? Which could hold the most weight?” This is the beginning of every experiment below, because a material’s properties decide what it is good for.

Five experiments from the bin

1. The strongest newspaper tower. Roll sheets of newspaper tightly into tubes and tape them. Challenge the child to build a tower that holds a small book. Then test: does a thicker roll hold more? Does a triangle shape beat a square? Change one thing at a time and write down what happened.

2. A rain gauge. Ask an adult to cut the top third off a clean plastic bottle, flip it upside down into the base like a funnel, and mark millimetres up the side with a ruler and a permanent marker. Put it somewhere open and check it each day. This links neatly to weather watching, and you can compare days.

3. Cardboard tube ramps. Cut a paper towel tube in half lengthways to make a track. Roll a marble or a small ball down it from different heights and measure how far it travels. A taller ramp should send it further; test whether that is true every time.

4. Which container keeps a drink warmest? Fill several different containers (a jar, a cardboard cup, a foil-wrapped jar) with warm tap water, not hot. Measure the temperature at the start and after 20 minutes. Which loses the least? Why might that be?

5. A bottle-and-straw sound maker. Fill identical clean bottles with different amounts of water and blow across the tops, or tap them gently with a spoon. Children hear that the pitch changes. Ask which has the higher note and why.

Make it a real experiment

Choose one of the above and ask three questions:

What are we changing?
What are we keeping the same?
What will we measure?

If you answer all three, you have a fair test. Younger children can simply say “I think this one will win,” then check.

Talk about where it all goes

When you finish, ask what could happen to the materials next. Could the tubes become something else? Could they be recycled again? You do not need an answer to everything. It is enough to notice that stuff has a life before and after we use it.

Keep the gear

Set aside one box labelled “science stuff” and drop clean tubes, jars, lids and bottles in as they appear. Next time a question comes up, the equipment is already there.

A note on mess and time

Most of these take 15 to 30 minutes, and the cleanup is mostly dry. Put a tray or an old tablecloth under anything involving water, and keep a damp cloth handy. If a child loses interest halfway, that is fine. Leave the materials out and come back later; many children return on their own and extend the idea in a direction you did not expect. Take a photo of the finished build or the result so the child can look back and see what they made.

Where to go next

If you enjoy this, try the rainy day science ideas, see how to set up a home science box, or look at the kitchen chemistry lessons. For a fair-test lesson you can teach at home, try What is a fair test?.