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That Sinking Feeling

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That Sinking Feeling

In this quick activity, learners observe how salinity and temperature affect the density of water, to better understand the Great Ocean Conveyor. Learners observe what happens when they add freshwater and saltwater ice cubes to a fishbowl nearly full of water. A brief explanation included in this resource explains why the ice cubes behave differently and how it relates to the motion of the Great Ocean Conveyor. This resource also explains how thunderstorms relate to air density and how to keep safe during a storm.

Quick Guide

Preparation Time:
4 to 24 hours

Learning Time:
5 to 10 minutes

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

Age Range:
Ages 6 - 14

Resource Types:
Activity, Demonstration, Lesson/Lesson Plan


Materials List (per group of students)

  • Fish bowl (or large, deep glass container such as fish tank, bowl, or pitcher)
  • Food coloring
  • Table salt
  • Ice cube tray
  • Water


  • Earth and Space Science
    • Earth Processes
      • Weather and Climate
    • Earth Structure
      • Oceans and Water
      • Atmosphere
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
    • Chemistry
      • Solutions
    • States of Matter
      • Liquids
      • Gases
      • Changes of Phase
    • Structure and Properties of Matter
      • Volume and Density
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Formulating Explanations

Informal Categories

  • Nature and Environment


To use this activity, learners need to:

  • see
  • see color
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



  • All Rights Reserved, National Weather Service,


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