Liquids in different shaped vessels. Liquid, in this case coloured water, is made up of very loosely connected molecules that are able to conform to the vessels they are put in. Adults take for granted that liquids take up the shape of the vessels that hold them, but it is novel for young children. Also notice the neck of the violet bottle; the colour of the dyed water is very pale but the same depth of colour is affected by the thickness of the vessel so it appears dark violet lower down. The same applies to the orange air trap where the balls, with greater depth, appear red. Red, orange, yellow, green, blue and violet; the colours are arranged in the order of the spectrum of light.