Dunking the Planets

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In this demonstration, learners compare the relative sizes and masses of scale models of the planets as represented by fruits and other foods. Learners dunk the "planets" in water to highlight the fact that even a large, massive planet — such as Saturn — can have low density. They discuss how a planet's density is related to whether it is mainly made up of rock or gas. This activity is part of a sequence of activities focused on Jupiter's immense size.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
$10 - $20 per group of students

Age Range:
Ages 8 - 14

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


Materials List (per group of students)

  • (5 1/2"-wide) large mango or potato
  • (4 1/2"-wide) large unpeeled orange, coconut, or cantaloupe
  • (2"-wide) plum
  • (2"-wide) kiwi or lime (not a lemon)
  • (1/2"-wide) small grape
  • (1/2"-wide) large blueberry
  • (1/4"-wide) pea or navy bean
  • (1/5"-long) uncooked orzo pasta
  • 1 (18" wide x 8" deep or larger) bowl, tub, or small wading pool
  • A sink or other access to water
  • 1 golf ball or ball bearing (optional)
  • 1 ping-pong ball or a marble that is similar in size to the ball bearing (optional)
  • "Dunking the Planets" pages
  • Pens or pencils


  • Earth and Space Science
    • Astronomy
    • Earth Structure
      • Rocks and Minerals
    • Solar System
      • The Planets
  • Mathematics
    • Measurement
      • Units of Measurement
    • Representation
  • Engineering and Technology
    • Engineering
      • Metallurgy and Materials Engineering
  • Physical Sciences
    • Motion and Forces
      • Gravity
    • States of Matter
      • Solids
      • Gases
    • Structure and Properties of Matter
      • Atomic Structure
      • Mass and Weight
      • Volume and Density
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results

Informal Categories

  • Food and Cooking
  • Outdoor Activity


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities