Recycle and Reuse
Grade Level: K-2
In this lesson students will explore how grass clippings, leaves, and other natural debris can be recycled and reused through composting. They will observe and record the changes in temperature and volume that occur during the process of decomposition.
Students will be able to:
- Measure the temperature and height of the compost jars
- Describe the changes that took place to the yard waste as it decomposed
- Explain the benefits of composting yard waste
- 30 minutes for Engage
- 45 minutes for Explore (plus time to record data every other day for two weeks)
- 45 minutes for Explain and Evaluate
Materials for the teacher:
- access to online resources
Materials for students:
- bag for debris collection
- clear glass or plastic jar
- plastic spoon
- small spray bottle filled with water
- container of soil
- magnifying glass
Teacher Note: If possible, arrange to begin this session on the day after your schoolyard is scheduled for mowing.
- Introduce to students that there are many tasks that people perform to keep their outdoor surroundings pleasant and usable. Ask students, for example, what people usually do when grass or bushes in our everyday environments becomes overgrown. Ask students if they know what happens to the grass that is cut or the branches that are trimmed. Remind students that in the fall, leaves change color and fall to the ground. Ask students what happens to those leaves.
- Take students on a tour of the school grounds to observe and collect evidence of cuttings, clippings, leaves, and other natural debris (twigs, bark, pine needles, etc.). Provide a bag or container in which to collect these items. Let students know they will be investigating what can happen to these items over time.
- Give each student group a clear glass or plastic jar, a plastic spoon, a container of soil, and a small spray bottle filled with water. Each group should also have their bag of cuttings, leaves, twigs, or other natural debris previously collected.
- Instruct students to spoon about 2 inches of soil into the bottom of the jar.
- Instruct students to spoon a layer of schoolyard debris on top of the soil.
- Instruct students to spray enough water into their jars to dampen (but not soak) the contents.
- Instruct students to continue layering soil and debris until they have filled their jar about 3/4 full. They should spray just enough water to dampen each layer after it has been placed in the jar. The top layer should be about 1 inch of soil.
- Have students use the ruler to measure the height of the soil/debris in their jar and record it in their science journals under Day 1.
- Have students insert their thermometers about 1/2 way into the jar and record the temperature of their soil/debris. They should also record this information under Day 1.
- Finally have students sketch their jar in their science journal under Day 1.
- Set the jars near a window. Every other day, have students observe their jar, measure the height and temperature of their soil/debris, and record the information under in their science journal.
- At the end of two weeks, have students use a spoon to gently stir up their mixture. Have them remove a few spoonfuls from the jar and examine them with a magnifying glass. They should record what they see in either words or sketches in their science journal.
- Have students share the results of their investigation. What trends or changes did they notice in the height of their soil/debris layers? What did they notice about the temperature? How did the spoonfuls they removed after two weeks compare to the items they placed in the jar in the beginning?
- Write the words decompose and compost on the board. Ask students if they have ever observed what happens to a fruit or vegetable when it begins to get really old. When it gets dark, smelly, and mushy that means that is beginning to decompose, or break down. Another word for decompose is rot. Anything that was once living can decompose. The items they collected (grass, leaves, twigs, etc.) once belonged to living plants. That means that these items can also rot, or decompose. When things have finished decomposing, they looks like a rich soil that we call compost. It is full of nutrients from the once living things and can be used to help grow new plants.
- Visit the site http://aggie-horticulture.tamu.edu/kindergarden/kidscompost/cover.html to learn more about the process of composting.
- Explain to students that in order for things to decompose, they need to be exposed to air, water, and decomposers. The soil that was placed in layers between their debris contained tiny microscopic decomposers. Decomposers are living things that helped their debris to decompose. Microscopic means they are so small they can only be seep through a microscope. Just like us, decomposers need air, water, and food. Ask students where they think the decomposers got their food (clippings, leaves, etc.).
- Explain that when some people mow their lawns, they let the clippings fall back into the grass where they naturally decompose. Other people collect their clippings in a bag when they mow. Some people add their clippings to a compost bin or place it in an area where it can decompose naturally. Other people place their clippings in bags and send it a landfill with other garbage. In landfills, the clippings are often not exposed to the air, water, and decomposers needed for them to turn into compost.
- Divide students into teams to implement preparation and planting of the garden. You may assign tasks such as Help students brainstorm the advantages to composting instead of throwing yard waste in the garbage (less waste in landfills, don't have to spend money on bags to collect the waste, compost that is produced can be used for garden and planting, save on buying compost from the store). Have students create a poster encouraging people to compost their yard waste.
- Take the compost quiz challenge at http://www.squiglysplayhouse.com/Games/Quizzes/Nature/Compost.html
To extend the learning:
- Visit the site http://yucky.discovery.com/flash/worm/ to learn more about worms as decomposers. Have students add a composting worm (red wigglers or European night crawlers are recommended) to their composting jars and observe the effects.
- Students can continue the composting process for several more weeks until their jars are fully composted. Have students use their composted material for planting or find a useful place to add it to the school grounds.
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National Science Education Standards Addressed:
- Simple instruments, such as magnifiers, thermometers, and rulers, provide more information than scientists obtain using only their senses.
- All organisms cause changes in the environment where they live. Some of these changes are detrimental to the organism or other organisms, whereas others are beneficial.
- Soils have properties of color and texture, capacity to retain water, and ability to support the growth of many kinds of plants, including those in our food supply.