My kids have a fascination with colored sand. They love to gently sift through it and see how they can create their very own rainbow as they pile up the different colors one on top of the other. It is like being the creator of their own universe - their glass bottle universe, that is.
So that day, my dining table was reincarnated as an indoor sand table. I poured the different colored sands into different containers and placed a plastic spoon in each to prevent the colors from mixing. I had them make two activities with it, sand painting and sand art bottles. I gave them each a small clear glass bottle with a natural cork cover for the sand art bottle. For the sand painting, I just chose an image from the net (of their choice, of course) and printed it our on board paper.
This activity was one of the easiest to do, almost no supervision needed.