Try your hand at making your very own Mini Miss Splish Splash.

What to do:

1. Using the scissors under an adult's supervision, cut the scraps of materials into squares measuring approximately 20cm by 20cm, and put to one side.
2. Pour the water into the crisp tube so that it is about a 1/3 full.
3. Take one of the samples of material and place it over the opening of the tube.
4. Secure the material in place with the elastic band, making sure that the material is pulled tight and that all the material's edges are tucked under the band.
5. Place the postcard flat on top of the material, shiny side down.
6. Place one hand flat on top of the postcard and hold the crisp tube with the other.
7. Now carefully turn the tube (with the postcard still in place) upside down, making sure that you keep the postcard flat at all times.
8. It's now time for the moment of truth. While still holding the crisp tube, carefully slide away the postcard. Two things can happen, either the water will all come gushing out onto the ground, or it will stay exactly where it is - inside the tube!
9. Remove that material and test the others. Try and guess if the materials will stop the water flowing out or not.

Here we see surface tension in action. Water has a high surface tension and this means the surface of water has a sort of invisible skin on it, pulling it back into the container. Surface tension is so strong that it can hold water together even across a hole, which is why some of your materials don't allow the water to flow out even though they are full of small holes.

But this is only half of the story; the other half is to do with air. For the water to get out, air must be able to get in. So when the material only has small holes in it, not enough air can get into the tube to push the water out. However, if the material has larger holes in it, then the surface tension will not be able to stop the air from getting into the tube. This means that air can now get into the tube to push the water out - and all over you!