Top image: Hand holding soil (photo by Jing via Pixabay)

Setting the Stage

All soils are not the same. They are a mixture of water, air, minerals and organic matter. Soil is formed over time from the breakdown of rocks. The size of the rock particles in soils determines the soil texture as cobble, sand, silt or clay. The particle size and amount of organic matter in soil also impacts on the amount of air and water it can hold and how the soil interacts with water.

This inquiry could begin from:

  • placing a bowl of soil on the table to elicit the students prior knowledge about soils. List their ideas in the Know column of a K-W-L chart. Discuss using questions such as:
    • "What do you know about soil?"
    • "Is all soil the same? How is it different?"
    • "Where have you seen soil like this before?"
    • "What are some names that we call different types of soil?" (e.g., sand, potting soil, clay, etc.)
  • collecting samples of soils from around the neighbourhood, school yard or home. Discuss using questions such as:
    • "How would you describe this soil (e.g., colour, smell, size of particles)?"
    • "What senses can we use to compare the soil samples?"
    • "How can we extend our senses even more to observe this soil (e.g., use a hand lens or microscope)?"
  • Screen shot from Whats the dirt on dirt?
    Source: SciShow Kids via Youtube

  • watching a video such as Whats the Dirt on Dirt? to learn about the four main components of soil. Discuss using questions such as:
    • "What things did you already know about soil?"
    • "What new information did you learn from this video?"
    • "What are the parts of soil?"

Materials and Preparation (Click to Expand)

Materials:

  • variety of soil samples (e.g., sandy soil, gravelly soil, loam, potting soil, clay soil, peat can be obtained at hardware stores or garden centres) - labelled for reference (Soil #1, Soil #2, etc.)
  • containers to hold soil samples, enough for each group
  • clear containers with tight-fitting lids (e.g., small mason jars, plastic lab sample jars)
  • stir sticks
  • hand lenses or other magnifying devices
  • sieves, colanders, coffee filters and other filtering devices
  • water
  • newspaper or plastic table cloths (optional)
  • latex-free gloves (optional)

Preparation:

  • Collect an assortment of different types of soils for students to compare and contrast. These samples could be collected from the school yard, neighborhood or brought in by the students.
  • Working with soils is messy. Consider collecting newspaper to cover tables or using plastic table cloths to facilitate cleaning up after the exploration.
  • Set up material sourcing stations, organized by type of material. Alternatively, organize an assortment of materials to be provided to each student or work group.

What To Do

Students develop the skills of observing and comparing and contrasting as they explore the composition and characteristics of soils.

Students:

  • use the materials provided to explore the components of soil
    • Educator prompts students to try using different tools and processes (e.g. adding water and shaking and allowing sample to settle) to separate the soil into components.
    • Educator encourages students to talk about the feel, look and smell of the soil samples.
  • Compare and contrast the characteristics of the various soil samples. The samples can be compared for texture (particle size), smell, colour, ability to clump, ability to pour and other criteria identified by the students.
    • Educator facilitates student exploration using probing questions (e.g., "Can you see the individual particles in this soil?" "Why do you think this soil is so dark in colour?").
    • Educator prompts students to provide descriptive words to characterize the soil samples
  • record the results of their observations on an organizer of their choice, using words, pictures or photographs.

Assessment

Observe and document, using anecdotal comments, photos and/or video recordings, students ability to:

  • Observe - students observe the characteristics of the soil samples using as many senses as possible as well as extend their senses using magnifying devices in order to notice the characteristics of the different types of soils.
  • Compare & Contrast - students use their senses to find similarities and differences in the characteristics of the soil samples.
  • Recording - students use descriptive language, pictures or photographs to summarize the results of their explorations.

Sand with handprint
Source: Efraimstochter, Pixabay

Fist squeezing dirt
Source: AlexVan, Pixabay

Co-constructing Learning

Students:
Saying, Doing, Representing

Educator Interactions:
Responding, Challenging

Students use the materials provided to examine the samples of soil

  • "What do you observe about the texture of this soil?"
  • "How can you tell if there is moisture in the sample? "
  • "What senses can you use to explore the soil?"
  • "Does soil have a smell? What does this soil smell like?"

Students work collaboratively to explore and manipulate the soil sample to determine what it contains.

  • "What criteria will you use to compare these samples?"
  • "When you put the soil through the sieve or colander, what happened? "
  • "What happens when you add water to the sample?"
  • "Does anything interesting happen when water is poured onto the soil?"
  • "Are there any measurements you can make to compare the samples?" (e.g., time for water to flow through a sample, size of clumps, etc.)
  • "How will you record your information?"

Students compare and contrast the characteristics of the different soil samples.

  • "How were the soils alike? How were they different?"
  • "What size of soil particles does this sample contain?"
  • "How did the size of particles in the sample affect the way that water soaked into the soil?"
  • "Were you surprised by any of the results? Why or why not?"

Students record the results of their exploration on an organizer of their choice, using words, pictures or photographs.

  • "What would be a good way to organize your observations?"
  • "Would a photograph or a drawing provide a better representation of these observations?"
  • "Can you include any measurements in your observations?"
  • "What are the units of measurement? Have you included the units of measurement in your organizer?"

Cross-Curricular Connections

Literacy

  • Ask questions that lead to additional inquiries about soils
  • Making inferences and extending understanding (e.g., about the composition, characteristics, origins, potential uses, etc. of the soil samples)
  • Communicate thoughts, feelings and ideas (e.g., use descriptive words to characterize the features of the soil samples)
  • Use specialized vocabulary (e.g., Each time we put the mixture through the sieves, more and more particles of the soil got trapped. Then we could see them better.)

Mathematical Thinking

  • Measure and describe the relative sizes of soil particles using non-standard measurement (e.g., large, medium, small, very small or fine)
  • Use standard units to measure the size of certain particles (e.g., The gravel pieces in this sample are about 3 to 5 mm in diameter.)

Extending the Learning

If your students are interested in learning more, the following may provoke their curiosity:

  • Show your students pictures of types of soils in different locations, and being used for different purposes. Discuss using questions such as:
    • "How would you describe the soil shown in this picture?"
    • "What do you think is the purpose of the soil? What other things is this type of soil used for?"
    • "Why do you think the soils are different colours? "
    • "What interesting or creative things can be made from different types of soil?"

Gravel road
Source: goodfreephotos_com, Pixabay

Soil scientist classifying soils
Source: Natural Resources Conservation Service, Wikimedia Commons

  • Show students photos of people working in soil science careers. Discuss using questions such as:
    • "What is this person doing?"
    • "What tools or instruments is this person using?"
    • "Why is this soil career important?"
    • "What skills do you think you need to be this type of scientist? "
    • "Does this sound like an interesting career? Why or why not?"
  • Students could apply their learning and skills from this inquiry to Design & Build a Soil Sifter, in which students design and construct a prototype soil sifting system that separates a soil mixture into large, medium and small particles.

Engineering Aide classifying soils
Source: United States Navy, Wikimedia Commons