Teacher's Guide - Where in the World of Soils - Soils Types and Regions

Where in the World of Soils

Introduction
Soils are found everywhere on Earth, but not all soils are the same. The soil beneath your feet depends on where you are—whether it’s a grassy prairie, a forest, a desert, or a frozen tundra. Each soil has unique characteristics that affect how it looks, feels, and behaves. These differences are the result of how soils form over time, influenced by factors such as climate, living organisms, parent material, and length of development.

Scientists study and organize soils using a system called soil taxonomy, which groups soils into categories based on shared characteristics. There are twelve major soil types, known as soil orders, each with distinct properties and typical locations around the world. For example, some soils form in wet environments rich in organic matter, while others develop in dry regions or areas affected by freezing temperatures.

For younger students, this concept can be explored by comparing soils from different places and recognizing that soil varies depending on the environment. Older students can deepen their understanding by examining how soil classification reflects formation processes and environmental conditions. This section helps students connect geography, climate, and ecosystems to the study of soils, while also emphasizing that soil is an important natural resource. No matter where we live, the soil beneath us plays a critical role in supporting life and must be understood and protected.

Learning Objectives: 

• Recognize that soils differ depending on location and environmental conditions.
• Explain how soil-forming factors influence differences among soils in different regions.
• Describe how scientists classify soils into groups (soil taxonomy) based on shared characteristics.

NGSS Connections:

• ESS2.A: Earth Materials and Systems
• ESS2.D: Weather and Climate
• PS1.A: Structure and Properties of Matter

Click here for a Powerpoint  (Note: The revised slide deck will be linked here.)

Discussion Questions: 

Background information to support a discussion: 

• Having a basic understanding of the characteristics and locations of major soil types will help you guide your students’ exploration. This guide highlights the key features and general locations of each of the twelve soil orders in the U.S. (and some tropical/subtropical regions).  Resources are provided below.
  • Soil Taxonomy (all Grades) This is a PDF for a poster of all 12 orders plus individual PDFs for each order.
  • State Soils Booklets - SSSA (All Grades) This has information and booklets for all of the state soils. Also includes an activity.
  • World Soil Orders - (Grades 8+) This is a world view of where each soil order can be found. 
  • The Soil Orders in the United States - USDA-NRCS Clicking on each soil order will show more information and a map of that order’s distribution in the US.  This is a great way to show where the order is found and the landscape, land use etc. connected with each.
• Soils are grouped into 12 major orders based on characteristics like how they formed, their mineral content, and the environment where they develop. You can think of soil orders as broad “families” of soil, each with a unique story about the climate, vegetation, and land processes that shaped them.  They are summarized in the table below.

Tips for Leading the Discussion: 

• Don’t get stuck on technical names. Students need the main idea: “This soil comes from volcanoes” (Andisols) or “This soil is frozen most of the year” (Gelisols).
• Focus on the “story” of the soil. Where it is found, what plants grow there, and why it looks or behaves the way it does. Example: “Mollisols formed under grasslands, so they are very dark and fertile because grasses add organic matter to the soil.”
• Use relatable examples. Compare soil features to familiar experiences: sandy soils feel gritty, clay soils stick together, organic soils smell earthy.
• Highlight patterns across the U.S. Use maps or classroom visuals to show where soil types appear, which helps students connect soils to climate and vegetation.
• Encourage observation and comparison. If students can see or touch soil samples, ask them to describe texture, color, or smell and match it to what they’ve learned about soil types.

Questions

1. Why are soils different in different parts of the world?

• Soils are different because places have different weather and plants.
• Soils differ due to variations in climate, organisms, parent material, and time.
• Soils differ because of climate, vegetation, organisms, time, and the material from which they form. Example: Aridisols in deserts are dry with little organic matter, while Mollisols in grasslands are dark and fertile. Use a map to point out different soil orders and their locations. Ask students to guess why a soil might be sandy, clayey, or organic. 

2. What is soil taxonomy and why do scientists use it?

• It is a way to group soils that are alike.
• Soil taxonomy is a classification system that organizes soils into groups based on shared properties and formation processes.
• Soil taxonomy is a system that groups soils with similar characteristics and formation processes. Example: Andisols all form from volcanic ash, making them fertile and easy to identify. Compare soil classification to grouping animals or plants. Ask: “How would you group soils that are sandy vs. clayey?”

3. How is classifying soils similar to classifying plants or animals?

• Things are grouped by what they have in common.
• Classification systems group organisms or materials based on shared characteristics to better understand patterns and relationships.
• Classification systems organize items based on shared traits. Soil orders are like “families” of soils. Example: Spodosols all have acidic, sandy soils under conifers, like a family of soils with the same characteristics. Encourage students to sort soil samples or pictures into groups, just like they might sort leaves, flowers, or animal types.

4. What can soil tell us about the environment where it formed?

• Soil can show what the place is like.
• Soil properties provide evidence of climate, vegetation, and geologic history.
• Soil properties reflect climate, vegetation, and geologic history. Example: Gelisols with permafrost indicate tundra climates; Histosols show wetland conditions with lots of organic matter. Ask students to look at soil color, texture, and organic content to infer what kind of environment it came from.

5. Why is soil considered an important resource?

• Soil helps plants grow.
• Soil supports ecosystems, agriculture, and human structures, making it essential to protect.
• Soil supports plants, ecosystems, agriculture, and human life. Protecting it ensures healthy food and environments. Example: Mollisols in the Great Plains are vital for crop production, so erosion or degradation could threaten food supply. Discuss human impacts like farming, deforestation, and urban development. Ask students how soil might be protected in their own community.

Suggested Activities and Curriculum Connections

• Soil Around the World Mapping Activity
  • Students match soil types to different environments (forest, desert, tundra).
  • Students analyze global soil maps and explain how climate and geography influence distribution.
• Soil Comparison Investigation
  • Observe and compare different soil samples (color, texture).
  • Measure and analyze soil properties and relate them to formation conditions.
• Soil Classification Activity (Taxonomy Simulation)
  • Group soil samples based on visible similarities.
  • Create a classification system and compare it to real soil orders.
• “Where Am I?” Soil Clue Challenge
  • Students guess a location based on simple soil clues (wet, dry, sandy).
  • Use detailed soil descriptions to infer climate, organisms, and landscape.
• Local vs. Global Soil Investigation
  • Compare local soil to pictures of soils from other regions.
  • Analyze how local soil fits into broader classification systems.
• Cross-Curricular Connection: State Soil Research
  • Research and present their state soil.
  • Investigate how their state soil formed and classify it within soil taxonomy.