Find a natural source of moving water like a small creek or water moving in the gutter after a rainstorm.
If these aren't available, you can make your own moving water by running water from the faucet into a stopped-up sink or running a hose over a hard surface. Remember to keep the faucet or the hose turned down low, at least at first!
Gently place some objects that float into the water and notice how the objects move across the top of the water.
Which way do they go?
If you are using a hose try moving it around. Does the object move in a different way?