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Scientists describe all matter on Earth as having constant molecule motion. Particles in a gas are moving rapidly. Particles in a liquid move quickly but not as fast as a gas. The particles in a solid typically vibrate in place.

Using a microscope, you will be able to observe random motion as you do this activity. If you do not know how to use a microscope correctly, please ask a teacher or responsible adult to assist you. Your success in this activity depends on your eyes being able to stare. Perhaps the staring contest you did with friends will help you now!



  • Microscope
  • Microscope slide
  • Cover slip
  • Two percent milk
  • Eye-Dropper

Safety concerns: icon icon Be sure to keep all chemical and glassware safety rules. Remember not to put a stopper into any flask unless given direct instruction by your teacher. Handle the microscope with care.



  1. Place a drop of milk on a microscope slide.
  2. Add a cover slip.
  3. Place the slide on the microscope stage and focus, using low power. (Focus on a "fat globule.")
  4. Move the microscope lens to medium power.
  5. Observe the "fat globule" through the microscope.
    • Pick a fat globule and stare.
    • Look for the motion of the fat globules in two-percent milk. (This motion is called Brownian motion. The fat globules move because of the motion of the molecules in the milk. Even though you are unable to see the milk molecules moving, you can see the results of their motion.)


  1. Draw what a fat globule looks like as seen through a microscope.
  2. Diagram the motion of a single fat globule as observed through the microscope.
  3. Does the motion of the fat globule change as it is over the microscope lamp?

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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