Get out your notebooks, and make entries on a page labeled "soil." (Keep in mind that geologists never call it "dirt.")

We have a collection of dry leaves and sticks. Take up a handful, and see how easily the materials can be crumbled to resemble soil.

Compare the appearance and feel of the different types of topsoil that have been collected for this experiment. Some is "rich," and some is not. When you are out on a nature walk, or even driving around in a car, you can see that some areas have an abundance of plants, and other areas are barren. The colors of the soils are different, aren't they? Why is that?

Dead plant and animal matter decays and builds in thickness to become what is called "humus." The "rich" soil has some humus mixed in with it. The poor soil does not. Probably the best soil has more humus than those that are less rich.

Mix some humus with the soil taken from a barren spot, and note how the humus changes the color of the soil.

If possible, take a nature walk, and notice where topsoil is built up and where it has been washed away.

In what kinds of places does the topsoil seem to be deepest? Since it takes about 300 years to produce one inch of good topsoil, we can assume that places where it is deepest has been undisturbed for a long period of time.

Use rulers to see how deep the topsoil is. After you have measured the depth of the topsoil, scrape some away, and you will see that topsoil is darker than subsoil.