Soil and Decomposers

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SWBAT describe why soil is important in an ecosystem and what living and nonliving components make up soil.

Big Idea

Energy transfers through an ecosystem through plants and animals and soil plays an important role in this energy transfer.

Lesson Overview- 5 E Lesson Planning

5 minutes

Unit 4: Ecosystems

Lesson 8: Soil and Decxomposers

5E Lesson Planning:

 I plan most of my science lessons using the BSCS 5E Lesson Model: Engage, Explore, Explain, Elaborate, and Evaluate.For a quick overview of the model, take a look at this video.

 I use this lesson model because it peaks the students' interest in the beginning during the "Engage" portion and allows for the students to actively participate in the investigations throughout the subsequent steps. The “Evaluate” component of the 5E Lesson Model can be used in many ways by the teacher and by the students.

 A great resource for lesson plan frameworks and explanations is the Community Resources for Science. The 5E Planning Sheet and 5E Lesson Promptscome from this website. 

 Unit Overview:

In this Unit students will learn about ecosystems and the transfer of energy through ecosystems. The lessons in the unit are primarily based on our local ecosystem- the Santa Monica Mountains. This area is known as a Mediterranean Ecosystem or Biome and we will learn about the plants, animals, climate, and human impacts on this area. 

Lesson Overview:

In this lesson, students will learn about what role soil plays in an ecosystem and what components make up soil.

Materials Needed:

  • 5 or more different soils samples
  • plastic bags
  • gardening shovels
  • gardening gloves
  • Clear plastic jars with lids
  • hand lenses
  • Science Notebook

* If you are collecting soild samples from around your school campus, make sure to get permission from you principal. If you don't have access to soil, have your students bring different samples from home, or make your own. 

 Next Generation Science Standards:

 he NGSS standards that will be covered in this unit/ lesson are:

5-PS3-1. Use models to describe that energy in animals’ food (used for body repair, growth, motion, and to maintain body warmth) was once energy from the sun.

 5-LS1-1. Support an argument that plants get the materials they need for growth chiefly from air and water.

 5-LS2-1. Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.

 Disciplinary Core Ideas:  This lesson aligns to the Disciplinary Core Ideas of

PS3.D: Energy in Chemical Processes and Everyday Life  The energy released [from] food was once energy from the sun that was captured by plants in the chemical process that forms plant matter (from air and water). (5-PS3-1)

 LS1.C: Organization for Matter and Energy Flow in Organisms  Food provides animals with the materials they need for body repair and growth and the energy they need to maintain body warmth and for motion. (secondary to 5-PS3-1)  Plants acquire their material for growth chiefly from air and water. (5-LS1-1)

 LS2.A: Interdependent Relationships in Ecosystems  The food of almost any kind of animal can be traced back to plants. Organisms are related in food webs in which some animals eat plants for food and other animals eat the animals that eat plants. Some organisms, such as fungi and bacteria, break down dead organisms (both plants or plants parts and animals) and therefore operate as “decomposers.” Decomposition eventually restores (recycles) some materials back to the soil. Organisms can survive only in environments in which their particular needs are met. A healthy ecosystem is one in which multiple species of different types are each able to meet their needs in a relatively stable web of life. Newly introduced species can damage the balance of an ecosystem. (5-LS2-1)

 LS2.B: Cycles of Matter and Energy Transfer in Ecosystems  Matter cycles between the air and soil and among plants, animals, and microbes as these organisms live and die. Organisms obtain gases, and water, from the environment, and release waste matter (gas, liquid, or solid) back into the environment. (5-LS2-1)

Crosscutting Concepts:

Systems and System Models  

A system can be described in terms of its components and their interactions. (5-LS2- 1)

 Energy and Matter  

  • Matter is transported into, out of, and within systems. (5-LS1-1)  

  • Energy can be transferred in various ways and between objects. (5-PS3-1)

 Science & Engineering Practices:

Developing and Using Models:

 Modeling in 3–5 builds on K–2 experiences and progresses to building and revising simple models and using models to represent events and design solutions.  Use models to describe phenomena. (5-PS3-1)  Develop a model to describe phenomena. (5-LS2-1)

 Engaging in Argument from Evidence

 Engaging in argument from evidence in 3–5 builds on K– 2 experiences and progresses to critiquing the scientific explanations or solutions proposed by peers by citing relevant evidence about the natural and designed world(s).  Support an argument with evidence, data, or a model. (5-LS1-1)


10 minutes

When the students walk into the science room they see a pile of soil/dirt at the front of the room on my demonstration table. I hear a few of them chatting to each other and wondering why I brought a pile of dirt into the science room. I wait until everyone has settled and whether or not they ask any questions.  A brave raises his hand and asks: "Ms Mutch, what's the dirt for?" I of course respond with "I am glad you asked- this is actually soil, also known as dirt". The students nod their heads and I ask them why soil is important, especially for plants? 

I tell to write their thoughts down in their science notebooks and I tell them to do a "Timed-Pair-Share" with their shoulder partner to answer the question. I have students share their answers and I write these on the board: food, water, nutrients, air, and support for the roots. 



20 minutes

I then tell the students that we are going to study different soils on our school campus and that each group is going to collect a different kind of soil. I have already picked some different parts of our school campus to collect the soil samples and I got permission from my principal to collect these samples. 

Day 1:

I give the students a plastic bag and a small garden shovel to dig up some soil. I have gardening gloves also if they want to use them. I tell the students to collect at least a half cup or about 150ml of soil and that we are going to bring these samples back to class to investigate the samples further. 

When the students return to the science room, I have them put the soil on a white paper plate and have them use toothpicks or small wooden stirrers to separate the larger particles from the soil and sort the soil. I also have them look at the soil using hand lenses. I tell the students to draw what their soil looks like in their Science Notebooks as well as to write any observations they have. I also have the students describe where they got their soil from (or draw it) as well as describe what was growing in that spot as well as anything else of importance. Soil components (sample that teacher made) 

I then have the students place their soil sample (about 1/2 of a cup) in a jar with a lid (a large jar works best, but smaller jars or plastic vials are a good option also.) I then tell the students to add a cup or so of water to their soil but  to make sure to leave some room in the jar (this allows for proper mixing of the soil and water). I then tell them to place the lids on their jars and to shake up the soil and water to mix them together. This only needs to be done for a couple of minutes. After they are done shaking the jars, I have the students draw and record their observations. I tell them that we will let the jars sit overnight to see what happens. I have them write a prediction about what they think will happen to the soils overnight. 

Day 2:

On the next day, we look at our jars and the students should observe that the soil has now formed layers in the jar. I have the students again draw what they are seeing (I encourage the use of colored pencils at this point so that they can distinguish the layers this way). I have them also describe their soil and we share the results with each other. 

Soil separation



30 minutes

After studying the different soils on our campus, I tell the students that they are going to  learn more about what makes up soil by going to this website and taking notes about the different parts of soil. This other website is also a good resource to fins out more information about soil. We also discuss the role of some of the arthropods that we found in the soil (pill bugs and earthworms). I tell them that these organisms act as decomposers and that they found information about them on the webite. 

I then show them this video to introduce the students to the idea that soil isn't the most important component for growing plants and this will lead us to our next lesson about plants.