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Your students' inquiring minds will provide fertile ground for extending soil investigations and activities. Here are a few ideas to get you started:

• Explore soil texture. Invite students to examine the texture of moist soils as scientists do. Set up stations with soil samples with very different textures: a sandy soil, a clay soil, and one with a lot of organic matter, for instance. Have students visit each station in small groups. Allow them to use a mister or squeeze bottle to moisten each sample until it is putty-like, then challenge them to try to form a ball with the soil.
  
  Next, ask them to press the samples between their index fingers and thumbs and try to form ribbons. Ask: How did the soils differ? Which soil would you want to grow a plant in and why? After discussing and sharing information on different types of soil particles, ask: Which seems to contain more clay? more sand? (The firmer and stickier the ball or longer the ribbon you can form, the more clay a soil contains. If a soil feels rough or gritty, and easily breaks apart or won't hold together in a ball, it contains sand. A loam will hold together at first when squeezed in your fist, but crumble apart when lightly touched.)



• Conduct a simple simulation to get kids thinking about erosion. Fill a shallow pan with soil, prop it up a couple of inches at one end to create a slope, and set up a collecting basin below the tray to collect runoff. Holding a watering can a foot above the soil, sprinkle "rain" for a minute or two. After helping students make connections between the simulation and what happens outdoors, challenge them to consider some ways farmers and gardeners might reduce erosion. Student ideas might include mulching, terracing, planting a crop of grass, or adding organic materials to improve water absorption. Have students design setups to test their ideas.



• Expand your horizons! Have students investigate the characteristics of natural soil layers or "horizons." You can view these layers best in an exposed bank or gully where the soil is exposed to a depth of 3 or 4 feet. The soil surface may have a layer of undecomposed organic matter. The next layer, topsoil, is typically looser and darker than lower soil layers because it contains the greatest amount of humus and soil life. The subsoil, which is more compact and generally lighter colored than topsoil, may begin a few inches or several feet deep. It contains little organic matter and few living things. Below this is weathered bedrock. After comparing the characteristics of topsoil and subsoil, students may want to predict which type will promote better plant growth, then experiment to test their hypotheses.