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Decomposition & Soil Structure Lesson Plan

Lesson plan for a 2-part lesson about soil and decomposition, composting, and more.

Decomposition & Soil Structure: Parts 1 & 2 Lesson

Lesson Plan

Decomposition & Soil Lesson Plan (PDF)


  • Submitted by:  Vince Case & Steven Henley
  • Content Area:  Science, grade 4 & 5
  • Materials Needed:  Paper, pencil, zip-lock bags, clear glass jars with lids, clear plastic containers with lids, rubber bands, plastic wrap or bags, digging implement, food scraps
  • Handouts Attached:  Observation log
  • Standard Addressed:  NGSS 5-LS2  Ecosystems: Interactions, Energy & Dynamics (see attached NGSS standards sheet for full information); 5-PS3-1:  Energy;  5-ESS2-1:  Earth’sSystems
  • Skill to be Maintained:  Making observations, considering what happens when things dies, asking scientific questions
  • Essential Questions:  What happens when things die in the ecosystem?  How do decomposers function within the ecosystem?
  • Academic Vocabulary/Word Wall words:  Decomposition, matter, detritivores (& vore), mycelium, scavengers

Basic Lesson Description and Procedure:

Part I - Decomposers

  1. Students watch the video from the SMNHC.
  2. Students review what we’ve learned so far in the first 6 videos – ecosystems, biotic & abiotic factors, parts of & interrelationships within ecosystems, scat, skulls, leaves, change over time.
  3. Students determine what is missing through viewing images of different kinds of mushrooms & mold – fungi!
  4. Students learn basics about fungi & bacteria as decomposers.
  5. Students understand the difference between decomposers & consumers which break dead things into smaller pieces through fragmentation (detritivores & scavengers fragment dead material into smaller parts).
  6. Students learn the definition of matter – the physical stuff that all things are made of.
  7. Students visit a composting facility where they see decomposition speeded up.
  8. Students recognize that decomposers return dead matter and the energy contained within it to the soil.
  9. Students make observations of food scraps and learn how to record these observations in an observation log.
  10. Students collect food scraps, seal them in plastic bags, and make observations over a 2-week period while recording in their observation log (see Activity #1 directions below).

Part II – Soil Structure

  1. Students observe the basic structure of soil (organic matter, top soil, subsoil, parent rock & bedrock) and how soil is formed.
  2. Students learn how to collect a soil sample in the video.
  3. Students make observations as we play in the soil for a short time.
  4. Students learn how to separate the layers of soil collected into the soil layers (organic matter, clay, silt, sand).
  5. Students learn how to record results in their observations by describing the sample area collected and drawing and labelling what they will see in the soil structure activity.
  6. Students participate in their own soil collection & layer activity (see activity 2 directions below).

Rotting Food Scraps Activity #1:

Students collect food scraps, place them in a closed, see-through container or zip-lock bag, and make observations of what happens to the rotting material over a 2-week period of time.

Soil Structure Activity #2:

Students collect a soil sample and learn how soil is composed of layers.

Lesson Conclusion/Potential Practice at Home:

Students share their observations & drawings with their families and others they live with.


Just about any grade level can do this lesson and activity

Rotting food scraps observation activity #1


  1. Collect at least 3 food scraps (orange & banana peels, pieces of bread, chicken bones, beans, rice, pasta, cheese) – whatever they can find and have at home.
  2. Place food scraps in sealable baggies (use rubber band or other tie if needed).
  3. Create an observation log with at least 4 columns & 15 rows (see sample below)
  4. Make observations daily for two weeks of each food scrap in their observation log.
  5. Observe changes in the decomposing food scrap samples over time

Soil structure activity #2


  1. Gather materials needed – clear glass jar or plastic container with lids or plastic bags & rubber band or other tie, small shovel or digging implement.
  2. With permission of adult, collect a sample of soil from outside.
  3. Add water to the soil sample, close lid, shake, and let sample settle for the night.
  4. Observe the soil sample the next day, recording your observations.
  5. Include a description of the soil sample location/site – what was there, what did you notice about the sample and its location, etc.
  6. Draw a picture of the settled soil sample and label the layers of the soil that you see in the jar or container (organic matter, clay, silt, sand, etc.) – see video for example of this observation record & drawing.

Observation Log Sample

DateSample #1Sample #2Sample #3