Use autumn leaves to teach about decomposition

A lot of what we teach in middle school science – carbon cycle, soil formation, recycling of matter, nitrogen cycle – relates to decomposition. Autumn present the perfect opportunity. Use your autumn leaves to teach about decomposition and get your students hooked with the real world applications.

Autumn leaves

Decomposition lesson plans using autumn leaves

It helps to start the unit with a brief unit explaining how things decompose and how that fits into the ecosystem.

My students have no idea what compost is. We’re a suburban upper middle class school district. Perhaps they have a tomato plant or two in their garden, but compost is foreign to them. So I start the year with some facts about compost.

Turns out every one of those statements is true. (TBH I was a little surprised about the masking tape.)

Here are some ways you can use autumn leaves to teach about decomposition:

1. Bring in some autumn leaves or take students on a walk if you have an appropriate area accessible to your school. Point out the various degrees of decomposition visible. Some leaves are still intact and others are falling apart. Lead students to question how that happens and how broken down leaves affect the ecosystem. Get down on the ground with magnifying glasses and see if you can find anything living in the leaf litter. Look for snails, slugs, worms, and centipedes as well as insects.
2. Use microscopes to examine decomposing leaves and identify the microorganisms and fungi responsible for breaking down the organic matter. Have students draw or photograph what they see and research the organisms’ roles in decomposition.
3. Take the exploration above and extend it by comparing what you see in a section of leaf litter to what you can see in a section of well-maintained lawn. Teach students about the benefits of biodiversity.
4. Collect different types of leaves and place them in separate containers with soil. Add moisture and observe which leaves decompose the fastest. Discuss factors that might affect the rate of decomposition, such as leaf thickness and moisture levels.
5. Conduct an experiment with various compostable objects and non-compostable into zipper bags. Put them away for a few weeks and then check them out to see how they change. Every middle schooler loves to watch things decompose.
6. Use a fish tank or other clear container to bury various objects in soil for a few weeks to months. Try to include something organic like a carrot or apple core and something petroleum based like a plastic spoon. Try soft objects like stuffed toys and hard objects like laminated playing cards. Let students make predictions then wait a few weeks or months and then uncover the buried objects. Don’t forget to take before and after pictures!
7. Create a mini-ecosystem in a terrarium in your classroom using autumn leaves, soil, and small decomposers like earthworms and pill bugs. Observe and document the decomposition process over time.
8. If you have access to an outdoor classroom, start a classroom compost bin with autumn leaves, food scraps, and other organic materials. Visit it often to monitor the composting process, noting how the leaves break down and contribute to the formation of nutrient-rich compost.

If you’re interested in seeing more about this unit, check it out in my TpT store here! Learn how to start a compost pile on my blog by clicking here.   Autumn provides a unique and tangible opportunity to teach middle school students about decomposition and its critical role in the ecosystem. If you use autumn leaves to teach about decomposition, you can create engaging and educational lessons that connect directly to key scientific concepts such as the carbon cycle, soil formation, and the recycling of matter.