Composting your classroom food waste with one bin, no smell, little effort, and a whole lot of worms.
Step 1. Get your students excited about worms
Start by inquiring into the United Nations Sustainable Development Goals and focus on food waste. Learn how much food your community wastes every year, and research ways to reduce food waste. We learned that even if you're a food waste avoiding ninja, you can still have fruit and veggie scraps like corn on the cob, banana peels, watermelon rinds etc. An inquiry into composting led us to vermicomposting (composting with worms) and we were hooked!
Step 2. Source your materials
I've built several worm bin designs with students but the simplest design for vermicomposting in the classroom is with 1 plastic bin.
Pro Tip: Always ask your school community for donations, check with maintenance staff, ask the teachers that are known to hoard materials, and shop second hand before buying new materials & tools.
1) 53L or more, plastic bin with lid (solid color, not clear)
2) A drill and quarter inch drill bit
3) Screen, cheesecloth or any breathable fabric like cotton
4) Staple gun, hot glue, art braids or whatever you've got on hand to secure the screen to the bin
Pro Tip: Avoid using tape as the bin will sweat and you will need to replace the tape often, which is not ideal for the zero waste classroom.
5) Shredded newspaper for bedding (avoid shiny paper)
6) Coconut coir
This absorbs extra moisture and reduces the need for bottom drainage holes and a second bin. The worms use this for bedding and also eat this and your castings will be packed full of extra nutrients with the addition of coconut coir.
8) Red Wiggler Worms
Check Facebook Marketplace, your local compost education society, or order online
9) 2L container for collecting food waste at lunch and snack
A yogurt container works well
10) A scale to measure weight of food waste
This is not necessary but it's a good way to incorporate some maths and track how many Kgs of food waste you saved from the landfill.
Step 3. Build your bin
Drill six large holes at the top of your bin, use a glue gun to glue breathable fabric or window screen over the holes on the outside of the bin. Soak a quarter of the block of coconut coir in water and add this to the bin. Add shredded newspaper and soak the paper until the consistency is like a damp wet sponge. You don't want your bin to be too wet that the worms will drown, but it needs to be damp enough that they're able to survive. (All living things need water!) Add your worms to the bin and leave them alone for about 4 days for them to get used to their new home and then you can start feeding them your food scraps.
Step 4. Feed the worms
Feed your worms around 2L of food scraps, once a week. It is best to feed only once a week to not disturb them too often. Download for a free printable information sheet about what to feed your worms.
Vermicomposting is a great activity for students to really understand nature’s cycles, connect students with nature, and take action towards food waste. In about three months you will be able to harvest your worm castings, (worm poop) and use these castings in your garden, or perhaps start a class business with your students and sell the casting or make worm casting tea to sell as a fundraiser. Share your worm castings with the community if you don't have a school garden at your school. Worm castings, also called hummus, is like black gold for the garden and is an amazing natural fertilizer. Over the summer, reach out to your community as chances are there are several avid gardeners among your school community that would be more than happy to care for your worms over the summer and use that rich black gold vermicompost on their own gardens.
Happy worm composting :)