BACKGROUND:
Worms play an important role in keeping the
soil in good condition. They eat microbes on the leaf litter
and pull down leaves into the soil as they tunnel. Their leftovers
help enrich the soil and make conditions better for plants.
Worm tunnels also help to get air down to
the plants' roots. Plant roots stretch down through the soil where
they can absorb the air, water, and nutrients needed for growth. Bacteria
and algae also inhabit the soil. They, along with fungi, earthworms
and other soil creatures play an important role in the decomposition of
organic material. Decomposers help break down dead plants and animal
tissue. Nutrients are returned to the soil, where they become available
to plants.
PROCEDURE:
- Prior to lab, ask children
to bring in worms, or ask for a volunteer to get worms. Stores that
sell bait may have live worms. Some children seem to better at worm
catching than others.
- Students should work in pairs, unless
each child brings in his own supplies. Fill the jar with alternating
layers of soil and sand so the worms will easily wiggle through.
Make each layer about 1 inch deep and spray each one with water so the
worms will easily wiggle through. Gently put the worms into the jar,
keeping them away from bright light. The larger the jar the more
worms it can sustain (e.g., a mayonnaise-type jar can hold about
5 or 6 worms.)
- Cover the top layer of soil with dead
leaves and then cover the whole jar with a dark cloth or put it in a dark
place because the worms have to think they are underground. Make sure that
students do not seal the jars tight since the worms need air to survive.
- After 3-5 days, have students look
at the worm farm and answer the questions on the lab sheet. Have
them write down what they observe. The worms will have tunneled through
the soil and sand, so that the different layers have begun to mix together.
They have also dragged the leaves down into the soil with them. Return
the worms to the soil, they will die if left in the jar.
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