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All matter is composed of particles which are in constant random motion. What is the effect of temperature on the speed of these particles? To answer this question, you will need to use some common materials and do an experiment. You will use food coloring and different temperatures of water to test a hypothesis.

Problem: How will differences in temperature change the rate at which food coloring spreads throughout water?


  • Two beakers or glasses
  • Warm water
  • Cold water (suggestion - add ice to water before using it)
  • Food color with dropper
  • Watch, clock, or stop watch


  1. Fill one beaker or glass with a measured volume of warm water.
  2. Fill the second beaker or glass with an equal measure of cold water.
  3. Make sure the water in both containers has seemed to stop moving after the container was filled.
  4. Carefully put one drop of food coloring in each container.
  5. Use the watch, clock, or stop watch to determine how long it takes for the food coloring to diffuse (spread equally) throughout both containers.

Instead of doing the activity, you may choose to use this link to view a QuickTime movie comparing food coloring put into hot and cold water.


  1. Which container did you expect to have the fastest diffusion of food coloring?
  2. How much longer did the food coloring take to diffuse in one container than in the other?
  3. How could you vary the water temperature to get the same results as this experiment?
  4. How do your experiment results explain the differences between the phases of matter?

Review science safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader , and Get Quicktime Player. (The Quicktime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE 7th grade science core.

Updated October 24, 2008 by: Glen Westbroek

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