Soil Structure

By Judy Bogle

Level:

Grade 6, Fourth Quarter, Weather and Climate (LPS Grade 6-8 Science Curriculum Guide, Text Scope and Sequence)

Summary:

Students will compare soil samples, use World Wide Web to research information about sand, clay and silt, and then make a model to show the relative sizes of grains of clay, sand and silt..

Key concepts:

  • Different soils are made up of varying proportions of clay, silt and sand
  • The diameter of grains of clay is less than 1/256
  • The diameter of grains of silt is between 1/256 mm and 1/16 mm
  • The diameter of grains of sand is between 1/16 mm and 2 mm

Materials Needed:

  • Soil samples
  • Styrofoam balls (or any objects that have diameters that differ from one another by magnitudes of powers of 10)
  • Paint, labels, pens, pencils, paper (to takes notes and to identify models for clay, sand, and silt)
  • Computers with internet connection

Learning Objectives:

  • To describe the composition of soil (LPS Grade 6-8 Science Curriculum Guide, Book: Earth's Changing Surface, Chapter 2: Weathering, Section 2: Soil Formation and Composition, Objective A)
  • To use the World Wide Web to research

Activity Preparation:

Gather materials listed above, arrange for use of computer lab and check to see that internet addresses are current.

Teaching Sequence:

Students work with a partner to:

  1. Compare the soil samples
  2. Write a description of how the soils are different from one another
  3. Use the internet address listed below for the Glossary of Selected Geologic Terms to research the diameter of the grains of clay, sand, and silt
  4. Write down the diameter in order from smallest to largest and label each
  5. Use objects to make a model and label it to show the relative size of clay, sand and silt grains
  6. Rewrite the descriptions of how the soils differ from one another using what you have found in the research and relating it to the soil samples

Possible Extensions of the Activity:

Use the internet address for the Glossary to find other words that you might use to describe the differ soils. Use the Conservation & Survey Division internet address to "Play Nebraska Geo-Trivia," or to view the MS PowerPoint Geologic Tour of Nebraska entitled "Nebraska, We're Not Just Another Pretty Interstate," or do interdisciplinary studies using "Fun Facts about Nebraska." Other activities related to teaching about soils can be found at the Nebraska Earth Science Education Network internet address.

Educational Resources:

  • LPS Grade 6-8 Science Curriculum Guide, Text Scope and Sequence, Draft Version 1999-2000
  • Earth's Changing Surface, pp. 49-56, Middle Level Science Curriculum, Prentice Hall Science Explorer 2000