Uplifting Force: Buoyancy & Density

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In this investigation, learners explore the force known as buoyancy by placing various objects into water and observing how they behave (for example, which sink more quickly, which float, how much water they displace and how air plays a role in keeping objects afloat). The introduction to the lesson tells the story of Archimedes, the Greek mathematician, who first discovered the law of buoyancy while attempting to determine the mass of a crown of gold.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 8 - 14

Resource Types:
Activity, Lesson/Lesson Plan


Materials List (per group of students)

  • marbles (15 per group)
  • medium to large plastic container--open topped, filled with water
  • 1/2 stick of clay
  • small airtight jar or bottle
  • pan balance or scale
  • student journals and writing tools


  • Earth and Space Science
    • Earth Structure
      • Oceans and Water
  • Physical Sciences
    • Motion and Forces
    • States of Matter
      • Liquids
    • Structure and Properties of Matter
      • Mass and Weight
      • Volume and Density
  • The Nature of Science
    • The Scientific Process
      • Asking Questions
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

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


Components that are part of this resource:

Includes alignment to state and/or national standards:

This resource is part of:

Access Rights:

  • Free access


Source Collection

  • Science After School Consumer's Guide


  • All rights reserved, State of New Jersey, 2006

Funding Source:

  • No Child Left Behind Act of 2001