Let's Find Out, RTÉjr's science show for kids, is all about answering the curious questions of the world around us - and Captain Zoom has a lot of questions!!

Watch the full show on RTÉ Player here!

The wheel has been around for thousands of years, and Zoom wants to know more, so scientist Amy calls on Amelia and Theo to help out with another cool experiment.

Find out how rollers made from logs were once used to roll heavy loads until the wheel and axle was invented.

As always, make sure you have an adult to supervise. Watch the video up top and follow the instructions below...

There is a full lesson plan here too...

You will need:

• A weighted object, like a small brick
• Four round objects like wooden rods (see video) or strong cardboard tubes
• A piece of cardboard
• A scissors
• A ruler
• A pencil
• Two straws
• Two wooden skewers
• A narrow cardboard roll (like those in the centre of a roll of aluminium foil)
• Four corks or plastic bottle caps.

What to do:

• First, see how hard it is to move the weight across a table by itself.
• Next, lay the wood or cardboard rollers out, side by side, with a little space between them.
• Lift the weight/brick onto the rollers and see how easily you can move the weight on the rollers, with just a little push.
• To keep moving the weight, remove a roller from the back and move it to the front (as in the video). You may notice that you can only move the weight a little at a time, and you need to keep moving the rollers.
• Now it's time to make a cart with wheels and see if that moves your weight more easily. Start by measuring out a square on a piece of cardboard, using the ruler and pencil. This square should be about the size of your load.

An adult should be asked to cut out this square of cardboard.

• Place a straw at each end of the cardboard and tape into place (see video).
• Put a wooden skewer through each straw.
• Now it is time to make the wheels; get an adult’s help with this part as the ends of the skewers are sharp.
• If using corks, simply push a cork onto the end of each skewer (remember to put the skewers into the straws first!
• If using plastic bottle caps, use something sharp (adults only!) like a corkscrew to make a small hole in the centre of each cap and push the skewers into these holes. Once again, make sure the skewers are in the straws first.
• Time to test your cart… place the weight/brick on top and push gently. Which is easier to move, the brick, the rollers or the cart with wheels?

The science bit...

Before wheels were invented, humans discovered that they could use something round and solid, like big wooden logs, to move very heavy objects.

But once wheels were invented, the job of moving heavier objects became much easier as the wheel was attached to an axle that allowed it to turn freely.

This meant the wheels could keep turning, moving the heavy object along, without the need to stop to move rollers all the time.