Unit 1: Back to the Earth
Lesson 1: Composting
Grade Level: Fifth Grade
Time Required: 45 minutes set up, several weeks for follow up and significant
preparation time! See Pre-Lesson Preparation section for details.
Primary AZ State Standards:
(Cross-reference “Standards Matrix” for full listing)
Science:
S05-S5C1-03: Describe physical and chemical changes of matter.
Objective(s):
Students will explain why it is important to recycle recyclables and compost
compostables.
Students will determine the best and fastest way to compost materials.
Students will describe the physical changes that take place in their compost piles.
Materials:
 Dirt
 Straw or dried leaves
 Food scraps
 Water
 A big shovel
 At least 2 pounds of worms (red wigglers are the best)
 A screen for sifting through finished compost.
 Appendix 5A: Compost Experiment Sheet
Traditional Outdoor Compost
 A roll of chicken wire or plywood and stakes (see PreLesson Preparation)
OR Vermiculture Boxes
 Plastic boxes (8 inches x 14 inches x 14 inches are
somewhat standard and easy to find)
 Newspaper
 Cardboard to fit inside the box as a secondary lid.
Key Vocabulary:




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Compostable
Recyclable
Vermiculture
Landfill
Carbon
Preparation
_X_ Adaptation of Content
_X_ Links to Background
_X_ Links to Past Learning
_X_ Strategies Incorporated
Instruction Features
Scaffolding
_X_ Modeling
_X_ Guided Practice
_X_ Independent Practice
_X_ Comprehensible Input
Grouping Options
_X_ Whole Class
_X_ Small Groups
__ Partners
__ Independent
Integration of Process
__ Reading
_(X)_ Writing
_X_ Speaking
_X_ Listening
Application
_X_ Hands-on
_X_ Meaningful
_X_ Linked to Objectives
_X_ Promotes Engagement
Assessment
__ Individual
__ Group
__ Written
__ Oral
Background Information:
Composting is a great way to make the mental connection between waste and
resources as well as life and death. So much of gardening and farming is focused on
getting seeds to grow, watering plants, and supporting life. However, gardens and
farms to replenish the soils with organic material through the process of
decomposition.
On many farms, old vegetation or cover crops are tilled under the soil and
allowed to decompose before replanting the fields. Smaller scale gardeners, however,
often have a compost bin that they maintain during part of the year, or perhaps the
entire year through. In their compost bin, gardeners will add vegetable and food
scraps from the kitchen or grass cuttings from the lawn, carbonaceous material such
as dried leaves or straw, worms, and small quantities of dirt. Each of these
ingredients is necessary to maintain a balanced and functional compost pile. The
green materials are a food source for the worms and nitrogen for the other
decomposers. The carbonaceous materials break down into organic material within
the dirt. Lastly, the dirt itself provides needed grit for earthworm digestion and
microbes for decomposition.
In addition, compost piles need air, water, and heat to really get going. Water,
heat, and air help the worms and promote quality conditions for decomposition. If
you are composting in a dry climate, it is important to add water to the pile from time
to time. The piles must be turned with a shovel on occasion to make sure the piles
stay aerated and don’t become waterlogged, anaerobic, and smelly! Finally, while the
decomposition process will create some heat, warmer outside temperatures will help
accelerate the chemical and physical decomposition process.
Compost is considered finished when there are no longer large, identifiable
chunks of composting material in it and the end product looks like rich dirt (in fact, it
will be mostly worm castings). Putting unfinished compost on gardens actually robs
plants of nutrients and stresses the plants. Consequently, only finished compost
should be used in the gardens by applying 1 -2 inches on the surface and then
working it into deeper layers of your soil before planting.
A popular form of urban composting is worm boxes, or vermiculture. A worm
box can be neatly stored under the kitchen sink, requires less processing (turning,
the piles and getting dirty), and produces smaller volumes of manageable compost
than a traditional compost pile. However, worm boxes operate off the same principles
and components as described for a traditional compost pile.
To build a worm box, take a plastic tub, drill holes in the bottom and along the
top sides for ventilation and drainage. Shred newspaper, moisten the paper (not
soggy!) and lay down several inches of newspaper to create bedding. You can also ad
dried leaves, since both newspaper and leaves are functioning as your carbonaceous
material. Throw in some dirt and bury a few pieces of kitchen scraps (green material)
to help the worms get started. Cut out a piece of cardboard and moisten it to create a
well-fitted lid. From time to time, add and bury more kitchen scraps in different parts
of the box as the worms eat it up. Just like a compost pile, monitor the balance to
make sure things aren’t too dry or too wet and that the worms have enough to eat.
In this lesson, teachers can opt to use either a traditional compost pile or a
vermiculture box, depending on time of year, access to gardens, and availability of
resources. Students will need time over the course of the next 4 weeks to follow up
and maintain their experiments.
Pre-lesson Preparation:
At least a week before.
1. Gather materials needed for an outdoor compost pile or an indoor worm box.
Especially important is collecting worms. You can either collect worms from
outside by putting down wet cardboard on the yard overnight and seeing what
worms migrate to it, or you can order worms online.
2. Talk to the cafeteria staff about collecting trash and food waste for one day.
For traditional, outdoor, compost experiments:
3. Either set up some small, round enclosures (one for each group) with chicken
wire to keep out critters (such as raccoons, squirrels, or mice), OR set up a
more sturdy (and expensive) structure that can be partitioned for each group,
particularly if the school will use it afterwards. To make a sturdier composting
area, take sheets of plywood and create a box by using stakes to hold them
upright and in place. Make sure one side is removable so students can access
it. Areas can be partitioned with smaller pieces of plywood.
For indoor vermiculture boxes:
4. Drill holes in the bottom and sides of boxes for ventilation before class.
Activity Instructions:
Sorting through trash
Whole class
10 minutes
1. Drag over a full trashcan from the lunchroom to the front of the class.
2. Ask students,
 “What can you tell me about this trash?” Comments will vary.
 “Where do you think this trash goes?” To the landfill.
 “If I asked you to sort through this trash (which they are NOT going to
do!), how much do you think would be recyclable? How much is food?
How much is real trash?”
Comments will vary. Encourage students to use percentages.
3. Tell students, “According to the US EPA (Environmental Protection Agency),
26% of our trash is compostable, and probably another 25% could easily be
recycled or reused.”
4. Ask students to explain the words ‘compostable’ and ‘recyclable’.
Compostable means it can be put into compost (organic trash pile) to
be naturally decomposed back into dirt. Recyclable means that the
materials can be processed again (at a recycling plant) and reused in
some other form.
5. Ask students to explain why we should care about sorting our trash.
Landfills are overflowing. Resources sent to landfills are not used
again, they are buried or sent out to sea. Recyclable material could be
used again, and compostable materials could be used to enrich the
soils with needed organic material. Taking those items out of trash
would also save on landfill space!
Composting experiments
Smaller groups of 3- 5
25 minutes
1. Tell students, “Today, I am NOT going to make you stick your hands into this
smelly trashcan to sort the trash but we are going to experiment with ways that
we can use the compostable materials for our gardens. Here are some scraps
from today’s/yesterday’s lunch, and some other materials that you need to get
started.”
2. Show students a sample of all the materials they will be using in their
composting experiment.
3. Explain the role of each material (green materials, carbonaceous materials,
dirt, and worms) as outline in the Background section.
4. Tell students, “Your job today is to create a composting guide for other
students in the school that explains the best way to make compost. You will
have to experiment with proportions and variables that may affect your
compost.”
5. Ask students, “What environmental variables would affect decomposition?”
Heat, water, air. Discuss information from Background with students.
6. Divide students into groups of 3-5.
7. Distribute Appendix 5A experiment sheets and have students fill out
predictions.
8. Explain how to set up compost experiments.
Traditional, outdoor compost
1. Inside each of the outdoor enclosures (either chicken wire or plywood), add
dirt, green material, and carbonaceous material. (Students get to decide how
they want to do this and how much of each material. They might also
consider whether they want to shred things well, or leave bigger chunks.)
2. Water the pile well.
3. Add worms.
4. Have students document on their experiment sheets how they set up their
pile.
Vermiculture box
1. Shred newspaper, moisten and wring out excess water.
2. Put down a 3- 4 inches of newspaper
3. Add several hands full of dirt.
4. Add some food scraps by burying them under the newspaper.
5. Add ½ pound of worms.
6. Cut a big piece of cardboard to fit inside the box as a secondary lid.
7. Wet the cardboard well and insert.
8. Put the box in a cool, dark place with the lid of the box underneath to catch
any moisture that drains from the holes.
9. Over the course of the next four weeks, have students record materials added
(green, carbon, dirt, water), when they mixed the soil, and any other treatments
they used. They will also record observations of how the materials are or are
not breaking down and how much final compost was produced by sifting final
dirt material through a screen.
10.
Discuss results as a group.
11.
In class extension  As a final, concluding project, have each group of
students make a brochure to distribute to the rest of the school promoting
their compost recipe.
Resources:
Wastes, Resource Conservation, Reduce-Reuse-Recycle, Composting. United States
Environmental Protection Agency. Accessed on June 30, 2010 from
http://www.epa.gov/epawaste/conserve/rrr/composting/index.htm
Extensions:
Willow Bend Environmental Center offers a 5th grade classroom program called
“Trash and the Three Rs” where students learn how to reduce waste, reuse
materials, and recycle in Flagstaff. Suggested fieldtrip “Recycling Tour”
through Willow Bend.