• Gather the following materials:
  • spring scale
  • shovel
  • grocery bags (5 to 8)

• Find an established wooded area. This is the most likely place to find a rotting log.
• Locate a rotting log.

• Remove a section of the rotting log and place it in a plastic grocery bag. Note: If the mass of the rotting log exceeds 1,000 grams, the Rotting Log Data Sheet will need to be adjusted.
• Collect a bag of moist leaf litter, a bag of topsoil, and a bag of subsoil.
• Choose three or more plants including some moss and dig them out with plenty of soil around the roots for protection. Place these in bags. Take care not to damage the stems or leaves.

• Gather Center Materials
  • 10-gallon aquarium with lid and light
  • bag of forest subsoil
  • bag of forest topsoil
  • bag of forest leaf litter
  • a piece of partially rotted log
  • two or more hearty forest floor plants with roots, stems, and leaves (e.g., Solomon seal, jewelweed, fern) and some moss
  • thermometer
  • scale

• Choose a location for the Center that allows for the display of multiple Background Information pages throughout the investigation. (See Ready to Print.)
• Copy a class set of the Family Page.

• Gather the class around the aquarium.
• Assemble the terrarium as follows:
  • Add subsoil to a depth of about two inches.
  • Weigh the partially rotted log, then place it in the terrarium.
  • Add topsoil to a depth of about an inch.
  • Add plants.
  • Add leaf litter.
  • Add a human artifact (e.g., Coke can) as a reminder of our impact on the environment.
  • Place the lid on the terrarium.
  • Place the terrarium near natural light or illuminate with the fluorescent lid light.
    

Note: The subsoil and topsoil layers should be moist like a wrung out sponge prior to adding them to the terrarium. Moisture can be easily added by using a sprayer. Avoid using incandescent light for your terrarium. Fluorescent bulbs provide healthier light for plants. Incandescent bulbs overheat the terrarium and can pose a risk of fire.

• Record the mass of the rotting log on the Rotting Log Data Sheet.
• Predict the mass of the rotting log for next week. Record this prediction on the Data Sheet in a different color. You may want to either choose an individual student, choose a table team, or take a class average for this prediction.
• Distribute the Family Page.

• Copy a class set of the Observation Page. These will be distributed to teams on their observation week.
• Make an overhead transparency of the Observation Page and the Rotting Log Data Sheet.

• Model observation skills by completing an Observation Page with the class. Discuss findings (e.g., millipedes at the surface, water trails on the glass from snails, the rotting log is heavier/lighter). Be sure to demonstrate how to record the mass of the rotting log without disrupting the terrarium plants.
• Introduce an overhead transparency of the Rotting Log Data Sheet. Connect data for weeks one and two as a class and discuss.
• Have students make informal predictions/hypotheses for the following week.
• Display the Observation Page and the Rotting Log Data Sheet at the Center.

• Assign three students to record observations on the Forest Floor Terrarium Observation Page and report findings to the class, including any patterns in the overall data (e.g., the rotting log is getting heavier/lighter).
• Plot new mass data on the overhead transparency of the Rotting Log Data Sheet as a class. Discuss patterns.
• Discuss background information as a class according to the following suggested schedule:
  • Week 3: The Forest Floor
  • Week 4: The Living Log
  • Week 5: Decomposition
  • Week 6: The Water Cycle
  • Week 7: The Needs of Living Things
  • Week 8: Bacteria (monerans)
  • Week 9: Fungi
  • Week 10: Food Webs
  • Week 11: Physical vs Chemical Change

• Have students make informal predictions/hypotheses for the following week.
• Display student Observation Pages and the weekly Background Information page at the Center.

• Check out Related Resources.
• Assign students to research a forest floor organism and share their findings with the class.
• Investigate algae in forest soil. Place two spoonfuls of soil into a clear container with a lid. Fill the container halfway with water. Add a leaf and tighten the lid. Shake the container and place it on a windowsill that receives sunlight. Within one to two weeks, you will see the growth of algae. Go further by using a microscope to study this algae's structure.
• Connect the layering of the Forest Floor Terrarium to the layers of the Earth's crust.
• Play a related song such as Dirt Made My Lunch. Versions of this song have been performed by Peggy Eyres or by the Banana Slug String Band.