1. Fill a sink or bath tub with water.

2. Practice tapping the cork on the surface of the water (about 3 _times per second works well) to create evenly spaced waves.

3. Tapping the water at the same frequency, move your object in a straight line in one direction in a broad, sweeping motion-not too fast, or you will have a hard _me seeing the effects!

4. As you move the object, try to observe the spacing of the waves extending in front of the object compared to the ones behind it.

5. Try a number of different speeds and tapping frequencies until you can see a spacing difference between the front and back waves.