Five fun activities that teach kids about energy

07 August 2014 | Rachel England

Kids know that flicking switches turns on lights and that radiators get hot when you turn the boiler on, but do they know why? These fun activities that will teach them about energy while keeping them entertained this summer.


Make a fruit battery

We all remember the clock potato experiment from our school days, and this project is essentially the same, but with a fruity twist! In this experiment, kids will learn how to convert chemical energy from the acid in a lemon into electrical energy.

You will need:

Four lemons (as big and juicy as possible)

Four pennies

Five zinc-galvanised nails

Five sets of alligator clips

LED light

Kitchen knife

  1. Use the knife to cut a penny-sized slit in all four lemons and insert a penny halfway into each.
  2. Push a nail into each of the lemons, opposite the penny (don’t let the nail and penny touch each other).
  3. Use the alligator clips to connect the penny of one lemon to the nail of another lemon – you should be left with two loose clips.
  4. Connect the loose clips and ta-dah! The light is powered by lemon energy!

How does it work? Find out here.

Learn about heat absorption

Dark surfaces absorb more light and heat than lighter surfaces, which reflect more light. This easy experiment shows kids how.

You will need:

Two identical glasses or jars



Elastic bands or sticky tape

White paper

Black paper

  1. Fill each of the glasses with the exact same amount of water.
  2. Wrap one of the glasses with white paper and the other with black paper, and secure with the tape or elastic bands.
  3. Leave the glasses outside in the sun for a few hours, and then check the temperature of each. The water covered by the black paper will be warmer, because its dark cover has absorbed more light and heat.

Learn about hot air

Kids grumpy because their bedrooms are too warm? This easy experiment will show them what happens to air when the temperature rises.

You will need:

An empty bottle


Pot of hot water (not boiling)

  1. Stretch the balloon over the mouth of the empty bottle.
  2. Stand the bottle in the pot of hot water and watch as the balloon expands.

Why does the balloon expand? The molecules in the air inside the bottle are ‘excited’ by the heat and start to move faster and further apart from each other. There is still the same amount of air inside the balloon and bottle, it’s just expanded as it heats up. Warm air takes up more space than cold air, which is why it rises in houses during the summer months.

See static energy at work

Most kids have witnessed what happens when you rub a balloon on your head – your hair stands up! This easy experiment illustrates how this static energy is real power and not just a crazy hair dresser substitute.

You will need:


Fluorescent light bulb


  1. Blow up the balloon and tie it off.
  2. Rub it vigorously against your head (or your child’s).
  3. Touch the balloon against the metal prongs on the bottom of the light bulb. The static electricity discharges from the surface of the balloon into the bulb, powering it to create light.

Learn the nitty gritty of the science behind this here.

Make a wind-up race car

You might already have a wind-up toy race car kicking about the house somewhere, but by making one yourself you can demonstrate the difference between potential and kinetic energy from scratch.

You will need:

A spool


Elastic band

Sticky tape

Metal washer


  1. Attach the rubber band to the toothpick in the same way that you’d attach a luggage label to a bag: lay the band out flat, lay the toothpick on top and pull the bottom loop through the top loop.
  2. Push the toothpick through the hole on the spool until it comes out of the other side, but keep a hold of the end of the rubber band.
  3. Pull the band taught so that the toothpick lays flat against the end of the spool, and then break off the edges of the toothpick so that they don’t protrude from the edges of the spool. Tape the toothpick down so it’s held in place.
  4. Feed the other end of the rubber band through the centre of a metal washer, then stick the pencil through the remaining loop of the rubber band. Twirl the pencil to twist the band fairly tightly.
  5. Put the spool down on a smooth surface, release it and watch it go!

How does it work? By twisting the rubber band you’re creating potential energy: energy that has potential to do something in the future, but is not doing anything at the moment. The more twisting applied, the more potential energy is created. Once the pressure is taken off the potential energy (the spool has been put down), the rubber band unwinds, converting the potential energy into kinetic energy, which is the energy found in moving objects.

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