Soils take on different properties depending on where and how deep in a landscape they are found.
Have students collect a soil sample from their backyard, immediately placing the sample in a one liter plastic bag to bring to school. They should document where and how they collected the sample. Encourage them to make as many notations as possible. In the classroom, have everyone set their samples out on paper plates. Once they've gained familiarity with their own sample, they can look around at others.