Molecules in Motion

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In this activity, learners add food coloring to hot and cold water to see whether heating or cooling affects the speed of water molecules. Learners watch molecular model animations to see the effect of heating and cooling on the molecules of a liquid. Learners will also draw their own molecular model.

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
45 to 60 minutes

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

Age Range:
Ages 11 - 14

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


Materials List (per group of students)

  • Hot water (about 50 °C) in a clear plastic cup
  • Cold water in a clear plastic cup
  • Yellow food coloring in a small cup
  • Blue food coloring in a small cup
  • 4 droppers
  • Goggles


  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
    • Chemistry
    • States of Matter
      • Liquids
    • Structure and Properties of Matter
      • Elementary Particles and Nuclear Physics
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

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