Before beginning a soil unit, ask students to draw or predict what they would find in a sample of soil. Then bring in or have students collect samples of soils from different settings: a building site, a garden, woods, and schoolyard, for instance. Invite each small group of students to examine a sample with hand lenses, toothpicks, and other tools, then describe the soil's color, texture, moisture, and smell. Ask students to identify, describe, and record the different materials they find. What evidence of plant and animal life do they see? Have groups share their findings with others and consider the following questions.
Are there differences in the types and quantities of living or once-living things? What do you think accounts for the differences? Which would you prefer to grow a plant in? Why? Have students generate a list of questions about soils prompted by their observations and discussions. Identify which questions they might actively investigate and which they might try to answer with other kinds of research.
Also consider starting a unit by asking students to draw concept maps beginning with the word "soil." Ask them to consider what other images or concepts the word evokes and how they might "connect" these images to illustrate their understanding.