Endless fun with things you probably have in your kitchen cupboard already.
What you need: Sharpened pencils, plastic food bags, water, paper towels (in case of spills), a sink to empty the water out afterwards.
Just fill a bag with water, pierce with pencils, and be amazed. The sharper the pencils, the lower the chance of any leaks. There's no trickery here – just science.
What you need: Bicarbonate of soda, vinegar, a container, a drop of washing up liquid, food colouring (optional).
The secret is to add a little washing up liquid to the vinegar before you mix them together. If you want to re-create this rainbow effect just add different food colourings too!
What you need: Washing up liquid, corn starch.
For a twist on the standard kitchen science experiment of adding water to cornstarch, add some dish soap instead. You can experiment by tweaking the ratio of soap to corn starch to get the texture you want.
What you need: Water, salt, gummy bears.
Compare how much gummy bears grow when you place them in salt water and plain water. Just make sure you don't eat the salty ones afterwards.