Teacher Site Map
7th Grade Core
USOE Science Home Page


Sometimes as we look at the world around us, we see movement without any evidence of why it happens. Consider the following and propose your hypothesis of what causes each.
  • 14 k gif image of clouds moving in the skyHave you lain on your back and watched clouds moving in the air above you?
    1. Did you observe anything pushing these clouds?
    2. Have you ever wondered what makes the clouds move through the sky?
  • 47k gif image of a flashlightNow shine a flashlight in a dark room and ask yourself the following questions:
    1. Do you see small particles in the air?
    2. Are any of these particles moving?
    3. What could make a dust particle move?

Now it is time to experiment and prove that

Purpose: You are to demonstrate the effect that temperature has on particle motion and volume.


You have already learned that the particles that make up matter are in constant motion. By increasing the temperature or energy in matter, the molecules speed up and the volume increases. The opposite is also true... by decreasing the temperature or energy in matter, the molecules slow down and the volume decreases.



  • Balloon
  • String
  • Marker
  • Bunsen burner
  • Matches
  • Two meter sticks


  1. Inflate balloon and tie off opening. (Use no more than eight breaths of air to fill up the balloon.)
  2. Wrap string around the widest part of the balloon.
  3. Use marker to mark the length of the string.
  4. Tie the balloon to the end of one of the meter sticks.
  5. Light bunsen burner.
  6. Use meter stick to hold balloon at least 500 cm (half of a meter) above the bunsen burner flame.
  7. After the balloon has been above the flame for five minutes, move the balloon away from the flame and quickly measure the width of it again.


Volume at start: Volume after heating for five minutes:


  1. Did the volume of the balloon increase or decrease after it was held above the flame?
  2. What kind of an experiment would you suggest doing to prove that cooling the balloon will also change the volume?

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

Science Home Page | Curriculum Home Page | 7th Science Core Home Page | USOE Home Page

Copyright Utah State Office of Education.