Here's another simple experiment we can do to gain a better understanding of erosion. This is an outdoor project. We can't be filling the school's drain-pipes with sediment!

Prepare a long U-shaped cardboard trough or a clear plastic pipe filled with coarse sand. Hold the cardboard in a slanting position over a pan, and pour water, a little at a
time, on the sand at the upper end of the tube.

You can see that as the water flows slowly out the tube, it carries small grains of sand with it into the pan, while the larger and heavier pieces are left behind. Take notice of the form of the sediment that is left when the water has all run out from the tube. Does it form an alluvial fan?

Now pour water into the tube or trough, using greater force. You will see that the sand and the larger pieces are washed downstream and you will begin to realize that moving water carries objects.

Start the experiment again, but this time, put some pebbles onto the top of the sand, and bury some pebbles beneath the sand. Look at the shapes of the sediment right after the water has passed the pebbles, and also check to see if the buried pebbles were exposed by the erosion of the sand.

You can experiment with the trough by raising and lowering it to see what effect the degree of slope has upon the transport and deposition of materials.

If you have the time, you could build a small hill and compact the soil with your hands so that it is fairly firm. With a small spade or other implement, form a creek that
starts at the top of the hill and meanders toward the bottom. Where the curves are formed, place some looser soil (soil mixed with sand would do nicely) at both the inside and outside edges of the creek. Place some pebbles along the creek; maybe even bury a few, or embed them firmly into the sides of the creek.

Using a sprinkling can with a nozzle that has several small holes, gently pour some rain onto the hill. Watch the water flow and the erosion, especially to and through the creek-bed. Fill the can again, and pour a hard rainfall onto the hill. Observe any effects of the rainfall.