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In this activity (on pages 25-31 of PDF), learners soak sponges with different amounts of plaster of paris to simulate different levels of calcification in bone formation. After being allowed to harden for 48 hours, the different simulated bones are tested by loading them with weight until they break. The lesson plan connects this to calcium nutrition and osteoporosis, and contains advice for building up calcium in bones. The activity is suggested for grades 5-8, but can be done as a demonstration for grades 3-4.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
1 to 7 days

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 8 - 14

Resource Types:
Activity, Demonstration, Experiment/Lab Activity, Lesson/Lesson Plan, Model


Materials List (per student)

  • Slightly moist sponges (not dry and brittle) enough for 3 cm. by 8 cm. (1.2 in. by 3.2 in.) sections for each student or group of students. It is important that all students use the same type and size of sponge so that comparisons can be made.
  • Scissors
  • Masking tape, labels, or permanent markers
  • Plaster of Paris
  • Measuring cups
  • Tablespoons
  • 16-oz. disposable mixing containers, one for each student or group of students (e.g., yogurt or cottage cheese containers)
  • Water
  • Stirring sticks, one for each student or group of students
  • Weighing scale
  • Old newspapers to protect work space


  • Life Sciences
    • Human Body
      • Skeleton
      • Health and Nutrition
  • Physical Sciences
    • Chemistry
      • Chemistry of Life


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Involves hands-on or lab activities


Includes assesments for student learning:

Access Rights:

  • Free access



Funding Source:

  • Regence Blue Cross/Blue Shield of Oregon