Experiment to find out what happens when food colouring is dropped into water, water and oil, and just oil.
3 clear cups - one filled with water, one with water and a layer of vegetable oil on top, one with just oil.
Food colouring - a couple of colours, preferably ones that'll mix to make other colours e.g. blue and yellow (green), blue and red (purple) etc. IMPORTANT: Ensure water based food colouring!
Prepare the 3 cups.
Tell the Beavers/Cubs etc. that you are going to drop some drops of food colouring into each of the cups (one colour first)
Ask what they think might happen doing the water, then water/oil and then oil only.
Water Only - Water changes colour.
Water/Oil - Some food colouring sits on top of oil for a while and some drops then drop through to colour water.
Oil - Drops stay as drops.
To extend add another colour to each.
Water only - water will change colour
Water/Oil - Some food colouring sits on top of oil and any that go through change the water colour
Oil - Drops stay separate.
Explain food colouring is water based and that is why it mixes. Oil doesn't mix with water and eventually floats on top.