Science - density tower

 Using water, milk, washing up liquid and oil I made a basic density tower. Using a spoon, you can pour the liquids gently on top of each other to create layers. Different liquids have different densities and different objects will settle upon the different layers.

Oil molecules have wide spaces between them. Water molecules are tightly packed. Detergent molecules mix with water molecules and milk is protein, water, sugars and a little oil.

In the real world, tanker ships carrying oil can sometimes accidentally spill leaving animals dying and suffering. An oil spill is difficult to clean up but because it floats on water, rather than mixing, the oil can be scooped or sprayed with detergents which helps to dissolve it.