Sedimentation occurs constantly in nature. Whenever floods occur, the floodwaters carry some sediment (soil) along the stream; sedimentation occurs when the flooding stops and the soil settles to the bottom of the river again. Natural sedimentation can form the basis of a science experiment that is appropriate for kids. In this experiment, kids take a sample of soil from a river and a sample of soil from the riverbed. Then, the students compare the contents of the soil inside the river to the soil from outside the river under a microscope. If the soil from the river has a significantly different physical structure, then the students can conclude it was placed there by sedimentation of soil taken from somewhere upstream.
Sedimentation can occur under controlled conditions as well as natural conditions. For kids in elementary school, simple experiments involving cups, water and sand may be the best tools for understanding the sedimentation process. For these experiments, you get several containers full of water, and then pour the sediment (soil, sand or any other particulate matter) into the containers. Then, you put the sediment into the water, and observe whether it settles to the bottom or dissolves into the water. If it settles to the bottom, stir it up to see whether it dissolves; if it does not, note that it sedimented fully.
Many different types of particles exist that are not soluble in water. Any one of these particles can potentially sediment in water. One easy experiment for kids on sedimentation involves adding several types of sediment into containers of water, and observing to see which one settles to the bottom the fastest. In this experiment, you simply pour equal amounts of different sediments into equal-sized cups of water, then watch the sediment settle to the bottom in each one. You record the completion of the sedimentation process when all the sediment has settled to the bottom of the container.
Sedimentation is not only a chemical and biological process. It is also a physical process, since the concepts of speed and velocity come into play heavily in determining how fast a type of particle will settle to the bottom. College-level projects measure the velocity of sedimentation using advanced diodes, which are inserted into the water. Of course, this kind of project cannot be replicated by children. However, children can do their own simple physics experiment by testing how different physical conditions affect the speed of sedimentation. In this exercise, the sediment is inserted into several containers where the water differs by various attributes: temperature, source (e.g., lake versus river versus bottle) and container shape. Then, the kids use a stopwatch to time how long it takes for the sediment to settle in each.