This is a little activity that my keeps my boys busy for up to an hour. Very simple, but fun, and they learn something too!
All you need is glass containers, spoons, water, and food colouring!
Fill a bunch of glasses with water, and put a couple of drops of one colour of food colouring into each glass. When you have a whole rainbow of colours, you can let the kids go crazy.
My boys love having little glass bowls and spoons and experiment mixing the colours. When the water gets too muddied, dump it out in the sink and start fresh.