K-3, Unit Three, Activity 2: "Life in a Log"

The students will investigate decomposers in a rotting log, and discover some of the organisms living there.

Grades: 1-3
Time: about 1 hour
Subjects: life science


  • Table knives, craft sticks, chopsticks, spoons, tweezers, etc.
  • Large jar with perforated lid (preferably plastic)
  • Magnifying lenses
  • Insect identification guide (helpful to teacher)
  • Flashlight(s)


  1. Bring sections of a partially decayed log into classroom in clear plastic bags.
  2. Distribute students around the sections in groups. Carefully pull apart portions of the log, using the tools. Keep interesting items in the jar for later observation.
  3. Have students observe the log at various depths- top, middle and bottom.
  4. Identify the insects and other items using the guides. Ask students: What kinds of organisms did you find? What were the differences at different depths?Why was it different at different depths?
  5. Chart the students' observations and discoveries.
  6. Sing (and perhaps march to) the "Decomposing March - sung to the familiar "count-off" chant used in the army. It is an excellent device for remembering the steps in decomposition, and teachers might like to teach it to the class during science or music lessons. It is a "march along" and does not need any music.

What can make a healthy tree
Into a dead one like we see?
That's de-com-pos-ing...part one!

Once the tree is on the ground
Decomposers break it down.
That's de-com-pos-ing...part two!

De-com-po-sers leave behind
Nu-tri-ents of every kind.
They make...
Good soil...
They make...
Rich soil...
That's de-com-pos-ing...part three!

In that so-il now we know
Brand new trees can start to grow.
From the...
Old tree...
Comes a...
New tree...
That's de-com-pos-ing...part four!

Have students draw and color the log section and organisms they observed.

Last updated: November 3, 2017

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