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In this geology activity, learners create a model using a mixture of salt and sand inside a CD case. When the case is tilted or inverted, the mixture dramatically sorts into a layered pattern. With this model, learners explore the angle of repose and Brazil Nut Effect to better understand how avalanches occur. Educators have the option of building the model with or without learners present. Includes a video demonstration of activity.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
1 to 2 hours

Estimated Materials Cost:
$5 - $10 per group of students

Age Range:
Ages 11 - 18

Resource Types:
Activity, Demonstration, Model, Simulation


Materials List (per group of students)

  • 2 CD jewel cases (regular thickness, not ultra-thin), with the inserts that normally hold the CD removed
  • Masking tape
  • Black sand (aka magnetic sand)
  • Salt (ordinary table salt, not rock salt)
  • Measuring spoon, 1 Tablespoon
  • Paper or plastic cup, at least 3 ounces
  • 4x6 card
  • Sheet of newspaper, or paper towel
  • Electric drill
  • Drill bit, 1/4 inch


  • Earth and Space Science
    • Earth Processes
    • Earth Structure
      • Rocks and Minerals
  • Mathematics
    • Algebra
      • Patterns
    • Geometry
  • Physical Sciences
    • Motion and Forces
      • Gravity
    • Structure and Properties of Matter
      • Volume and Density
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Model Building
  • Nature and Environment


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access



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