Managing A Classroom Worm Bin March 25 2010
I love worms.
Why? One simple reason: their poop is valuable.
Can anyone or anything else say that? I don't think so. If you've ever seen what worm poop - also known as "black gold" - can do to your garden, then you know how valuable worm compost can be.
I first brought worm composting into my classroom about ten years ago. I found my worm bin to be a valuable, cross-curriculum teaching tool that benefited my students, our school garden, and the earth.
Worms eat garbage; more accurately, worms eat natural waste, poop it out, and create an incredibly nutrient-rich soil to use in our gardens. Their needs are simple - air, darkness, warmth, a little water, and waste material - and easy to provide. They can be kept in a small bin, aquarium or box lined with heavy plastic that fits well in a classroom environment.
Making the Bin
Your classroom worm bin should be about the size of an 18-gallon tote. Make sure there is a loose fitting lid, and put air holes along the top all the way around the bin. Avoid material that is transparent - worms need darkness.
Some people drill holes in the bottom - I don’t, but that’s my preference. As the worms do their work and the compost in the bin heats up, a liquid is formed that’s called “Compost Tea.” This liquid is great for plants, but it will leak from your bin if you drill holes in the bottom. Instead of dealing with a possible leaky mess in your classroom, plan on removing the liquid every week or so using a turkey baster. Otherwise, if you choose to drill holes in the bottom, you’ll need a tray of some kind underneath the bin to catch the liquid.
Now that there are air holes, fill your worm bin about halfway up with bedding – I suggest damp, shredded newspaper and leaves. Although damp, the materials should not be soaked or soggy. Then add the worms. Red worms are the best for a worm bin, and these are called Eisenia foetida and Lumbricus rubellus. You can order these from a worm farm and have them mailed to you at your school. These worms are sent by the pound – start with one pound for your classroom bin.
What To Add and What To Avoid
Once inside the bin, worms will be ready to do what they do best – eat garbage. There are some guidelines to what you can put into a worm bin. Stick with coffee grounds, vegetable peels, egg shells, and raw fruit (avoiding banana and orange peels). Stay away from cooked meat and food, oils, dairy products and processed food. Bury the food about 4” into the bedding. A pound of worms should be able to eat about a cup of scraps a day.
Rotate the food around the bin, burying it in different spots. As you notice the bedding disappearing and replaced with nutrient-rich soil, push the contents to one side of the bin. On the empty side of the bin, put fresh, moist bedding and bury food scraps. The worms will migrate to the fresh side of the bin so that you can harvest the soil from the other side. You’ll have to do this every couple of months to keep the worms working well.
Although worms need warmth, it’s not good to have them in direct sunlight. Keep them in a corner of the classroom but still accessible to your students. Train your students to help take care of them – they’ll love it!
For The Class, Or Per Student?
Individual compost bins for your students are easier than you might think. Choose a plastic container for each student and have them paint the containers black - these could be 2-liter soda bottles, small totes, or a small wooden boxes that measure 5"x5". Look around and see if there are materials large enough that can be recycled, and have your students do the same, bringing in containers that might work.
After the containers are painted black, have students place or cut holes about 5 inches apart on all sides of the container using a pair of scissors or an awl (if this makes you nervous, have parent volunteers come in and help with this part). If the container has a lid, you won't need to cut one. If there isn't an opening, however, have students draw a 4" x 4" square and cut three sides of it, leaving a "hinge" on one side; secure the opening with duct tape once the container is filled and ready to go.
Then fill the bins with bedding a few worms. The bedding consists of moistened shredded newspaper. Place it inside the bins along with the worms and a couple of vegetable scraps. Have students place their compost bins in a safe place that isn't too cold or hot and out of direct sunlight.
After a couple of days, have your students check on their worms and make sure everything is working out well. If it isn't, you could always put the worms all together in a large bin.
However you decide to direct the study of worms, don't forget to point out how valuable worm poop is as compost material. This will grab your students' attention immediately, and make for a fun worm unit!