You will need: an old CD or DVD (check before you steal your mum’s favourite Take That album!), a sports-bottle cap (Fruit Shoot or similar), a balloon, Blu-tack.

Roll the Blu-tack into a sausage and use it to attach the cap the centre of the CD. Make sure the cap is closed. Inflate the balloon but don’t knot it, then carefully stretch the opening over the bottle cap (it helps if you twist the end of the balloon to stop it deflating while you’re doing this). Your hovercraft is now ready to go! Carefully open the cap and the air will start to escape from the balloon. This makes a ‘cushion’ of air under the CD so you should be able to skim it along a smooth surface (the floor is best). Why not decorate your hovercraft and race it against your friends?

See how to make this on the Fab Science YouTube channel

Think like a scientist:

• Try skimming it without the balloon (or with the cap closed), what do you notice?
• The cushion of air reduces friction between the CD and the floor, can you find out more about friction?
• Does the size of the balloon make a difference?

What happens when you poke a balloon with a sharp stick? Expecting it to go bang? Try out this impressive science trick to skewer a balloon without popping it (hopefully!).

You will need: balloons, bamboo skewers, vegetable oil.

First, inflate the balloon about half-way and tie a knot. Next, dip your skewer in oil to make it easier to push into the balloon. Now for the important part, choosing where to stick the skewer: look carefully at the balloon and you’ll notice that the area close to the knot is a little darker than the rest of the balloon, that’s because the rubber isn’t stretched as much. This means that if you make the hole there you might manage to avoid the ‘pop’. At the other end, there is another darker area, carefully push the skewer out at that point and you have a balloon kebab!

Note for parents: take care with sharp points and this should only be attempted under supervision. A cheap pair of safety goggles from a DIY store could come in handy.

Floating and sinking is all about density. We usually think about solid things floating or sinking in water. For example, a football will float on a pond as it is less dense than water and a bowling ball will sink as it more dense than the water. Using these same ideas about density you can make liquids float on top of each other with some very colourful results!

You need

• a glass or clear plastic beaker
• golden syrup (squeezy bottle is best)
• washing up liquid
• coloured water (use food colouring or fruit squash)
• cooking oil
• a spoon

What to do

First, pour about 1cm of golden syrup in the bottom. Try to avoid getting any on the sides of the glass. Next, carefully pour washing up liquid on top (try to pour it very slowly down the side of the glass). Do the same with some coloured water, even slower this time. Finally pour vegetable oil slowly onto the top, it’s easier if you run it over the back of a spoon. Hey presto, you’ve made a liquid rainbow, isn’t it pretty?

Think like a scientist:

• What happens if you carefully pour a few drops of coloured water on top of your rainbow? (watch from the side)
• Can you experiment with other liquids?
• You can try making your own liquids of different densities by adding different amount of salt or sugar to water.
• Which liquids are best for floating? Try floating the same thing in different liquids such as water, oil, juice, washing up liquid, golden syrup. Do some things float in one but not the other? Can we link this to the density of the liquid (think back to the rainbows)? This is a messy one but does you thinking about density! Good things to try are peas, small beads, marbles and sweets.

Don’t forget to show us your rainbows on the Fab Science Facebook group…we’d love to see what you have been up to!

Simply fill a small white plate with water (a few millimetres deep) and place a selection of Skittles or M&Ms around the edge. Keep it very still and watch as the colours travel across the plate. What do you think will happen when the colours meet? You might expect them to mix but you’ll probably find that you get perfectly neat lines instead! This is because the sugar and colouring that is dissolving from the surface of the sweet is spreading out by a process called diffusion. The sugar will move from where there is lots of sugar to places where there is less. When it meets more colour and sugar coming the other way, there’s no point going any further!

You can make your own colour-changing potion just using vegetables! You will need a grown-up to do the cooking bit.

Making the potion:
Roughly chop half a red cabbage and boil in just enough water to cover it for around 10 minutes. The water should turn dark blue. Keep the water and put the drained cabbage to one side. Leave it to cool.

Doing the experiment: You need some beakers (see-through ones are best). Put about 100ml of water in each one and add 2 tablespoons of the blue potion. Now get experimenting! Try adding different things to see if you can make the liquid change colour, you’ll need to give them a stir. Things you could try: vinegar, lemon juice, milk, liquid hand soap, toothpaste, bicarbonate of soda, washing powder… anything else that you can find (check it’s safe!). Try it again using beetroot instead of cabbage, do you get the same results?

Think like a scientist:

• Try to guess what colour each one will go before you do it.
• Can you change the colour back if add something else?
• Have a look at the cabbage, what colour is it? Would you want to eat it? How could you make cabbage stay red when it’s cooking? (look up red cabbage recipes for the answer!)
• The colours change because the things that you are testing are called acids and alkalis. Acids turn the liquid red or pink, alkalis make it go blue or purple. Can you find out about them in books or online?