Third graders in many jurisdictions learn about soil. Well ahead of starting that science unit, start an indoor composting bin for your class to observe.
Curriculum expectations are always based on the Ontario Ministry of
Expectations. Many of the activities will reinforce, rather than teach,
those expectations. As such, no assessment ideas or rubrics are
included.
Earth and Space Science
Overall Expectations:
- assess the impact of soils on society and the environment, and of society and the environment on soils;
- investigate the composition and characteristics of different soils;
- demonstrate an understanding of the composition of soils, the types of soils, and the relationship between soils and other living things.
Here are two outdoor activities that introduce your students to the magic of composting indoors. The second allows for hypothesizing and comparing.
Compost Chefs
For this exploration, please collect
- at least one clear plastic tote with a tight-fitting lid (think about how much room your classroom has, as the bins cannot be stacked),
- a polyester sheer material like a sheer curtain,
- duct tape,
- a class set of old forks and spoons,
- one shovel for you,
- some clear plastic cups, and
- a bag of recycled-paper pet litter.
If your schoolyard has a grassy area, you and your students can go outside or stay outside after a recess time on a day that the ground is not frozen. You are going to release the students onto the schoolyard with some firm instructions ("Stay where you can see me", for example, and "Whistle means gather around.") in order to find and bring you a little soil (in their cups). Soil from outside likely has many tiny critters in it. If you add much of it to your indoor composter, your classroom may become home to mites and moulds, as I have found out the hard way...
Also have your students bring to you organic materials -leaves, twigs, grass, weeds, anything that was once alive. Instruct those who come with any materials besides soil that they should crush the twigs, leaves, etc a bit with something, maybe their foot. Smaller pieces are better.
Then ask them to bring you as many red wiggler worms as they can find.
Fill your tote(s) only a third of the way so that you can carry it into the school, and so that the kids can add more materials as the months go by. Moisten the litter and cover the contents of the tote with the pet litter to avoid any soil life escaping into your classroom.
Ask your students what is going to happen to all this stuff? Explain that the soil is filled with decomposers that make the organic matter disappear! Explain also that this process teaches us patience because this disappearing will take months. Or... don't explain anything at all and observe together over months what happens.
Maybe you can celebrate Fridays by allowing students to check the bin, and add some organic matter to it. If there are a good number of red wiggler worms in the bin, they can add their banana peels or apple cores to the bin. Bury it under the pet litter, and don't overdo it with the lunch scraps or your bin will start to smell trashy. The bin should smell only earthy.
Do you have in your class a student with a strong will impressive leadership potential? Ask that student if he or she is willing to take charge of the compost bin for the next several months (And if you have several of those students, I guess you'll have to find several clear plastic bins or have them take turns being in charge). These leaders are responsible for keeping their peers from messing with the bins. They are also responsible for adding water to the bins when the material gets too dry (It should be no wetter or dryer than a damp rag.)
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| Wikimedia Commons: Robbieross123 |
Later in the school year, before the bin gets too heavy (maybe on Earth Day?), you and your students can have the Big Reveal outside. Find a place or plant on the schoolyard that could use some nutrient-rich soil, and dump the bin! Allow all the students to have a good look and make observations. Did a lot of the organic material disappear? Take pictures of the before and after and also of the students' reactions.
In addition, the Big Reveal can be combined with a presentation to fourth grade; they, in turn, will teach your third graders about the decomposers that did the work. More about that in the blog post coming up on March 19th.
Discuss composting and its role in waste diversion.
Compost Bottles
This idea allows each student to make their own composter. Some can be inoculated with fertilizer and others can have red wiggler worms added. Click here for the complete instructions and a picture of one class' findings. For additional information from the California Academy about this same activity of Sciences, please see this lesson.
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