Half fill (approximately) a clear plastic bottle with water and add some blue food colouring or paint. Then add enough baby (or vegetable) oil to create a layer on top of the water. Add some silver glitter. ***SECURE THE LID WITH GLUE OR TAPE***
Tip the bottle to see waves forming on the surface, with light reflected by the glitter – it should look like the ocean
How it works…
Waves form when wind blowing across the water transfers energy to it, which moves through it creating waves. Sunlight is reflected at many points on the water surface because it is irregular (rather than smooth and flat like a still pond), so that it appears to “glitter”
When you tilt the bottle, you are transferring energy to the liquid within it, so that you see movement
The sea is blue because large bodies of water scatter blue light in all directions and absorb other colours. It also reflects the sky above, which is blue because blue light is scattered most by particles in the atmosphere. The sea can also look green or grey, e.g. if it contains things like algae or sediment
Oil floats on water because it has a lower density than water, and does not mix with it. The oil creates a barrier so that the glitter stays at the top of the bottle; when it reflects light it creates an effect similar to that of the “glittering” ocean
Things to talk about…
(describe things to younger children, and discuss them with those that are old enough)
The colour of the sea – does it change in different places and different times?
What happens when waves get to the beach?
Can you make the waves bigger/smaller? (If the wind gets stronger or you tilt the bottle harder, more energy is transferred to the water so waves get bigger)
Are waves useful? Can they be dangerous? What happens to boats on the sea?
Can you see the oil on top of the water? Why isn’t the glitter in the water?