My son loves things that he considers to be ‘magic’…and is fascinated when this ‘magic’ has an explanation. Chromatography is a quick one that he loves to observe. Simply take a bowl with a small amount of water in, some filter paper (we used coffee filters), some string across the bowl, two pegs and a black marker pen. Draw some black blobs on the bottom of the filter paper and then place it in the bowl and peg it in place so that the water can rise up the paper. Then watch the ‘magic’ as the black separates out into its constituent colours!