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Activity

Worms: indoor compost bin

Summary: 
Make a compost bin with red wigglers, or small garden worms, that can be kept in the classroom/home. Other animals that are decomposers e.g. wood bugs, snails, slugs can also be added to the bin.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Classification of Living Things, Biodiversity (1, 3)
Biology: Life Cycles (2)
Biology: Food Webs, Ecosystems, Biomes (3, 4)
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Lessons activity is in: 
Materials: 
  • Large plastic tub with lid that fits snugly (though some air gaps smaller than a worm diameter ideal)
  • Newspaper
  • Water that has stood for two days to release chlorine, about 2 liters
  • Trays or tubs to wet newspaper in
  • Vegetable scraps
  • Red wiggler worms, or other worms suitable for indoor composting, in extra dirt. Purchased from the resource listed, or dug from a compost heap/garden
Procedure: 

Discuss what worms need to survive then assemble the worm bin to provide them with these things.
Air: the bin has holes in the lid, and the lid will be opened frequently to allow more air in too.
Water: worms need to stay moist (as they breathe through their skin, obtaining the oxygen dissolved in the water)
Food: worms eat rotting plants (and turn them into rich soil)
Darkness: worms burrow down away from the light to seek cool, damp places, and to hide from predators

Sit the class in a circle around the empty worm bin.
Worms need a moist environment - make a layer of wet newspaper in the bottom of the bin to keep the environment damp:
Distribute trays of water around the circle. Distribute a sheet of newspaper to each student. Ask the students to lay their newspaper sheet in the water, then crumple it into a loose ball (about 5-10cm diameter) to gently squeeze the extra water out. Pass around the worm bin for students to add their wet newspaper balls to it, to make a layer of wet newspaper balls covering the bottom of the bin.
Add the worms:
Add the red wigglers/small garden worms in a little soil. (Students can add worms they have been looking at.)
Worms need food:
Students can each add a piece of old vegetable to the bin, to form a scant layer. Do not add to much as mould growth on the uneaten vegetables can take over the worm bin. Avoid sweet fruits (apple cores, banana peels, orange peels) as this attracts fruit flies.
Cover the soil to keep it moist:
Students tear newspaper into long strips, then layer this on top of the worms and their food. This keeps the moisture in and any fruit flies out.
Place the lid on loosely.

Discuss how to take care of the worms:
The bin should be kept out of direct sunlight and away from heaters, to keep it cool.
Food should be added when the worms have consumed the previous food. Too much food will invite mould growth.
The bin should be kept damp but not soggy: worms need to stay moist, but will drown in too much water.
When the newspaper strips are getting broken up, mix them in and add a new layer on top.
After a month or so, the worms will have made new, rich soil from the vegetable scraps. This soil can be added to garden or potted plants as fertilizer.
Sometimes, plants will grow from the seeds added to the bin (see third photo).

See the worm bin care sheet for more detailed information (attached).
Also more information here: http://compost.css.cornell.edu/worms/moreworms.html

Dismantling the worm bin:
When the worm bin is taken down, the freshly made compost/rich earth can be separated from the worms and put on plants that need fertilizing.
Look out for baby worms, and even worm eggs (about 1mm long, dark red-brown and egg shaped with one pointed tip).
The worms can be put in a garden, or kept to make a new worm compost bin.

Setting up a second compost bin, from a previously made compost bin:
As above, make a layer of wet balls of newspaper in the bottom of the new bin. Take several handfuls of soil, rich with worms, from the old compost bin (you could use the entire bottom layer of soil and worms if this layer is not too deep). Layer over the old vegetables and dry newspaper etc, as described in the instructions above.

Notes: 

One bin was set up with worms collected by kids from the garden. It went well for three months before crashing, and we found a lot of water in the bottom of the bin. Try with small garden worms - avoid the huge ones - and make sure enough newspaper is mixed into the soil to keep it light.

Grades taught: 
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 6
Teacher: 
Anke Barabulea
Barbara Duncan
Bernard Wan
Carole Murray
Christy Wong
Ingrid
Kathryn Mazzone
Kecia Boecking
Linda Bierbrier
Mari Matsuo
Monika Pilat
Natasha Tousaw
Patricia Ellis
Teaching site: 
Bayview Elementary Science Club
General Gordon Elementary
McBride Elementary
Laurier Elementary
ProD for Elementary teachers
Selkirk Elementary
Sexsmith Elementary
Simon Fraser Elementary
Activity originally developed and delivered: 

Gordon Elementary School