Take a small bottle with a special cap on it for pouring out sand - I found them at my school, but if you clean out a white glue bottle and pull off part of the top to leave the inside portion, it would look the same. Poke holes in the bottom of it and push a pipe cleaner through it.
Tie this to a wooden dowel and suspend it above a large cardboard box. Place a piece of contact paper sticky surface up at the bottom of the box.
Have the children hold a small funnel on the jar. Fill it with colored sand and let it flow into the bottle.
Put the cap on and show the children how to keep the top covered as they tip it into the box and give it a swing.
Encourage the children to make predictions of what kind of shape the sand might make. Why did the red sand go in a different place than the blue sand? What do you notice about the sand? The children can change how they swing the bottle and compare how the sand falls with different swings. This activity can lead to a lot of rich discussion with the older children. The younger ones like to watch the sand fall and often like to control the bottle rather than let it swing. Remember...it is the process...