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Micro-Organisms - This Assignment Stinks!

Where does all of your garbage go after you’ve taken it to the curb? Believe or not, our microorganism friends, bacteria and fungi, play a very important role as decomposers. They feed on and break down plant and animal matter. Without these decomposers, the bodies of all organisms that have ever lived would remain. This would be pretty messy! When bacteria break down the dead organisms, they release substances that can be used by other organisms in the ecosystem.

One way people help to reduce the amount of trash that they send to the landfill is by recycling. Composting is a form of recycling that changes plant wastes into nutrient-rich compost. Your goal is to determine the types of items can be composted and the types that cannot, demonstrate the decomposition of, or lack thereof, several items, and compare and contrast the speed at which various items break down.

Safety Precautions:
Be sure to wash your hands every time you handle the compost material.

Based on what you know, form a hypothesis about what types of items will decompose in a compost pile and which will not.


  • At least four large glass jars
  • Soil
  • Water
  • Watering can
  • Banana peel
  • Apple core
  • Newspaper scraps
  • Leaves
  • Candy wrappers
  • Aluminum foil or Styrofoam


  1. Decide how you will test whether or not the items decompose. How will you see the items? You might want to research composting in books, magazines, interviews, or on the Internet.
  2. Copy the following table in your science journal for each material that you choose to test. Use this table to help you record your observations.
    1. Material:
      Day Observations–what does the material look like and smell like?
  3. Place each of your materials in their own jar. Remember, you need at least four materials. Cover each of the materials with the same amount of soil. Moisten the soil in each jar with same amount of water. Place them all in the same environment (your choice).
  4. As you check your jars every day, make sure you record your observations on your data table in your science journal. Do you have constants, a variable, and a control?

Analysis (record in your science journal):

  1. Did all of the items decompose? Which did, and which did not?
  2. Was your hypothesis correct? Explain.
  3. Which items decomposed the fastest? Which items decomposed the slowest? Why do you think this is so?
  4. What materials in our environment might prevent decomposition?

Relate it to your world…

Choose from the following writing assignments to show what you have learned about composting, decomposition, and their benefits to our environment.

  • Write a persuasive letter to the editor of your local newspaper explaining what you have learned about composting and encouraging your community to do more composting.
  • Write a letter of request to your local community leaders asking for information on building and maintaining a community compost bin as a school service opportunity.
  • Write a poem or song to educate the public on the benefits of composting rather than filling up our landfills.

The following link can explores "composting for kids" at home.

utah state board of education This Sci-ber Text was developed by the Utah State Board of Education and Utah educators.