One way erosion can take place is with the involvement of water. Water has a density high enough to be able to move small and medium size rocks. The physical movement of water over a rocky surface will cause small pieces of the rock to become dislodged, which makes it easier for water current to move the rock. For this activity, make a pile of sand on one side of a deep pan. Pour some water on the other end of the pan and shake back and forth to imitate waves. Record the observations to discuss later. Do this with a variety of sand or rocks for a variety of results.
Winds of various intensities will change the landscape through erosion accordingly. Since air is very light in terms of density, wind will not typically move large, heavy objects. One way to demonstrate how wind can alter the natural surroundings, set up a small activity. Fill a pan with sand. Turn on a hair dryer and point it at the sand to imitate wind. You can also use a fan to make the wind for the activity. Place a few small rocks in the pan to show how these large items can disrupt the flow of wind. The last variable of the activity is to spray a little water over the sand to show how a layer of moisture affects erosion by wind. This activity best imitates wind erosion that would be found in dry deserts.
Large ice formations can cause large amounts of erosion over time. As ice forms, it picks up pieces of land. When the ice moves, it also takes those pieces of land with it to another location. This is one way lakes have been formed in the past during glaciation periods. For this activity, freeze sand inside an ice cube tray; these will represent glaciers with rocks formed within them. Fill a few pans with small rocks, sand or dirt, each in their respective container. Drag the ice cubes along the surfaces and record the results. Also, leave a few ice cubes overnight so that it melts. The result should be a small deposit of sand from the ice formation. Bright colored sand from a craft or fish supply store will help illustrate the point better.
When erosion moves earth from one location, it will eventually deposit it in another location. This process is known as deposition, which goes together with erosion. Over time, a layer of rock will be put down, followed by another layer and so on. This stratified rock formation is referred to as sedimentary rock. A fun way to show this to students is to make their own rock formation. Begin by making a few holes in the bottom of a clear, plastic container; line with a coffee filter. Make a trench from foil with curved sides, just large enough to fit the sides of the plastic container, and secure with tape to the back of a baking pan. Using different colors of colored sand, put a small layer on top of the coffee filter. Place the container in a sink and prop the trench to drain into the container. Place some sand in the trench and slowly pour water down it. Change the sand and repeat to represent different layers. This will demonstrate both erosion and deposition.