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Rock fragments, minerals and organic matter make up soil, but how do big rocks get so small? It happens through a process called weathering. The weathering process is a lot like the digestion process that your body does. Rocks are "chewed" up by the wind, rain, and acids into smaller and smaller pieces. Weathering is always going on and things like the rock type, temperature, and moisture levels can influence how fast it can break down. In this activity, you will model the changes that are caused by weathering and erosion.


  • Large cake pan
  • Clay type soil
  • Pitcher
  • Water
  • Bucket
  • Items to incline the pan (such as books)
  • Sand
  • Gravel
  • Fist size rocks
Safety concerns: Be sure to keep all chemical safety rules. As with all science lab activities, the most important safety rule is to follow all teacher directions. In this experiment, be especially careful that water does not get onto the floor where you might slip and fall.


  1. Place the clay type soil into your large cake pan.
  2. Use materials such as books to incline the pan slightly at one end.
  3. Use the pitcher to slowly pour water over your soil starting at the top of the incline.
  4. Use the bucket to catch the sediments and water as they come out the bottom of the inclined pan.
  5. Make observations of the pan and sediments.
  6. Make a prediction what will happen with the next size.
  7. Proceed through each size of material as done at first.
      • Place one material into the pan.
      • Incline the pan.
      • Slowly pour water starting at the top of the incline.
      • Catch the sediments and water in the bucket as they come out the bottom of the inclined pan.


  1. How does the inclined pan represent the natural structure of rock materials found on Earth?
  2. What process on Earth does the water movement represent?
  3. How does water on Earth get to the top of mountains to start the natural process of erosion on Earth?


Obtain a rock tumbler and place different rocks into it. Observe the changes to each type of rock as you go through the various steps of the tumbling process. Be careful to note which kind of rocks survive the tumbling process the best.

Review Science safetey 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 8th grade science core.

Updated October 24, 2008 by: Glen Westbroek

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