Soil is a natural resource of inestimable value. It is classified as a renewable resource, but because it may take from a few hundred years to a few thousand years to be renewed, it is more accurately termed an exhaustible resource. The emphasis of this teaching unit is the importance of soil and the need and means to conserve it. The constraining principle behind these student exercises is that soil erosion is generally to be found outside, therefore teachers are urged to use the outdoors as the learning laboratory as often as is practicable. Alternative indoor activities are included when outdoor work is inconvenient. This unit includes a teacher's guide and student guide. Slide tape sets are available. The unit includes the following sections: (1) "The Importance of Soil"; (2)"Soil Loss--How Does It Start?"; (3) "Factors That Affect Soil Erosion"; (4) "The Effects of Soil Erosion"; (5) "Putting a Stop to Soil Loss"; and (6) "Planning Avoids the Problem." (KR)