Skip Discover Education Main Navigation
Skip Discover Education Main Navigation

The Dirt on Soil Down & Dirty Field Guide Soil Safari

Teacher Tips

Grade Level: 5-8
Curriculum Focus: Soil Ecology, Earth Science, Life Science

Project Overview
Online Components
National Standards Correlations
Using the Project in Your Classroom

Project Overview

What's the difference between soil and dirt? Students often think of soil as inert and dead, but the living systems that create and make up healthy soil are incredibly dynamic and complex. As long as they think of soil strictly in terms of something that simply holds plants up, students will not appreciate the ecological and biological processes that sustain nearly all terrestrial life on our planet. This project introduces students to the idea of soil as a living entity made up of a diversity of organisms living in a complex three dimensional habitat. It also helps students understand the interplay of physical and biological processes that shape soil formation and characteristics.

Online Components

Down and Dirty
This overview of soil ecology introduces students to the basic definition of soil and its structure. Here they'll learn about the soil profile as organizing concept of soil structure. Students can learn how soil forms by following a step-by-step "recipe" for making soil from solid rock. They'll learn how soil is catagorized according to the relative abundance of different sizes of particles.

Field Guide
This section profiles species selected from each major type of soil organism, ranging from the largest animals to live underground to the smallest micro-organisms. Each profile provides information on the organism's size and ecological role in creating and maintaing soil health.

Soil Safari
An interactive game shows students the importance of the organisms and physical structures in soil at different size scales. Start at a size of 300 mm and go down to 0.003 mm (3 microns). The same organisms profiled in the Field Guide appear here as characters in a goal-based learning game. Students are drawn through the exploration by a mission to find something living in the soil that can take care of a leaking toxic chemical.

And there really are bacteria that eat toxic chemicals such as toluene.

National Standards Correlations

From the National Science Education Standards, grades 5-8:

Life Science
*Plants and some micro-organisms are producers--they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem.

Earth Science
*Soil consists of weathered rocks and decomposed organic material from dead plants, animals, and bacteria. Soils are often found in layers, with each having a different chemical composition and texture.

Using the Project in Your Classroom

Soil Critter Trading Cards
Begin the session with a brief discussion on how animals have adapted to meet the challenges of the environment they live in and how each animal contributes to its environment. Pass out a
templatewith the instructions that as students use the Field Guide, they are to note the contribution an animal provides to the soil, along with basic information (its size, its food source) and any facts of particular interest to the student.

After they complete the activity, students refer back to their notes and create trading cards. These cards can then be used to evaluate students reading comprehension, understanding of how a variety of animals make important contributions to soil and their environment.

Soil Critter Food Web
For this activity, you'll need either the student trading cards from the previous activity, student access to the Field Guide, or have specified that students note the food source of each organism in the Field Guide. Each group or individual student will need a length of string, their Soil Critter Trading Cards or blank index cards, markers, pens and paper.

Remind students that energy is stored in organisms and is transferred to other organisms when they are eaten. A map of this transfer of energy is called a food web. Starting with the mole and earthworm, each written on a card or use a students trading card, connect the two with string. Have students review their notes with the question what else eats the earthworm? Connect to the correct animal. Have students complete the physical food web, either in pairs, small groups or individually. When they are done, pose the following questions for discussion or journaling:

  • What animal has the most variety in its diet?
  • What organisms would be most affected if another organism were to cease to exist? How would they be affected?
  • Are there any organisms that contribute more to the soil than others? Why?
  • Are there any organisms that harm the soil?
  • Are there more of one type of organism than another? Why would that be?

A final assessment could be a quick sketch with arrows colored to distinguish predator/prey relationships. A paragraph or two describing how a particular organism affects its surrounding ecosystem could round out the experience.

Soil Profile Replica
This activity reinforces order in which soil is formed. Students will demonstrate knowledge of what constitutes a soil profile by creating, in cooperative groups, either a mural on butcher paper or stacked dioramas depicting the levels of soil. You'll need bulletin or chalkboard space, five different colored strips of butcher paper, Soil Critter Trading Cards from the previous activity or cards with the names of the animals written on them. Students will need their notes or access to The Dirt on Soil. Arrange any art supplies for students in a centrally located station. If you are going to construct dioramas then, a week before you plan to teach this lesson, have students bring in an old shoe box.

Provide students with some time to read The Dirt on Soil. Allocate a space from your chalkboard or bulletin board. Divide the area with butcher paper, one color for each level. Label each level: ground level, topsoil, subsoil, weathered parent material and bedrock. Review that first came the bedrock then parent material, and so on. You might want to build your display by showing the bedrock layer, then attaching the parent material layer next, etc. Discuss key terms: soil profile, decomposers, humus, organic matter and parent material. Have a few describe what a soil profile is and then direct them that they will recreate the soil profile they just studied in poster (or diorama) form. Keep your mural'll be used to review later.

Split your class into groups. Have them review their notes and plan what needs to go into each layer. Once they have a plan, allow them to swing into action building or drawing their replica. After a set period of time but before they're finished, call the groups together with their plans and discuss what they've put into their replicas. Take what they've agreed upon and draw/write in on your mural. This serves as a check that everyone has the correct information.

To prepare the assessment, request that they correct their plans in a different ink. Thank them and have them return to their groups to finish. After their project is completed, have them review their plan. Anything that needed to be changed or added to their plan then becomes the last task: briefly describe the importance of each item that needed to be changed or added.

Investigate Soil in your backyard
Contact your local USGS office ( to determine where in your area you can find roadside cutouts that expose loamy, sandy and clay soils. These places can then be a suggested family outing or class field trip to take pictures or soil samples. (Get parental permission before students dig in the soil?some children are allergic to mold or spores which may be in soil. And have students wear plastic gloves whenever they touch the soil.) Alternatively, you could go out there, take pictures and soil samples. Regardless, try to collect enough samples to be divided among small groups of student in your class. If possible, locate a map of the area your school draws from and post-it notes. As they read through Name That Soil, require students to write in their own words descriptions of the three types of soil described.

Divide the samples evenly among groups of your students. Samples are compared with the notes from Name That Soil. Challenge them to order the samples to match the layers in the cutouts soil profile. Next, break the samples up so that each student has a sizable amount to take home and compare with the soil in their neighborhood (for urban areas, suggest nearby parks). Distribute a T-chart for them to compare the ground level and topsoil of their neighborhood with that of the cutout.

The next session, discuss their findings. Place on the map where the soil was loamy, sandy or clay. If there isn't a map, try to draw a schematic of the area that your school draws from. Discuss if the soil samples were similar or different. Could there be a reason for this (sandy soil means that sandstone was the bedrock that created the soil, etc.)? The local USGS might be able to provide more interpretation to the findings.

Soiled Poetry
This activity can be used as an assessment for the entire Learning Adventure. For students without much exposure to writing poetry, you could use a more formulaic approach: one stanza per layer, each stanza has a line for the critters that live in the layer, a line that identifies the layer and its features, etc.. Otherwise free verse form or, for more of a challenge, haiku or limerick would work.

Begin by webbing what your class has learned about soil. For each branch, come up with both scientific terms and descriptive words. Example: a branch about subsoil would contain the words subsoil, organic matter, humus, decomposed along with descriptive words like humid, fertile, vital, etc..

Students then pick off from the class web words that might help them write their own poem. The only requirement is that they fully describe each layer of soil and how organisms contribute to soil. The rest is up to creativity!

Home     &nbspDown & Dirty      Field Guide      Soil Safari
Resources      Teacher Tips      Credits