Clay is very fine and tends to be sticky. A good way to show these parts that make up soil is to use a small-diameter bottle or jar with a cover. Close the jar, shake vigorously for several minutes, then allow the soil to settle out. You will note that the sand which is heaviest will settle to the bottom first. Gradually the silt settles, followed by the fine clay particles.
Rain is the most common form.
Raindrops strike the earth with great force, and when striking on bare soil often cause compacting or disruption. Rain drops are like small bombs. By using two sheets of white cardboard, one placed on a grassy plot and one on bare ground, you can see the effects of the force of a rain drop and the resulting damage. Use a sprinkling can to create the shower of raindrops.