Wildlands Soils Experiment

Wildands Soil Experiment

Description: Students learn about the three basic groups of soil (sand, silt, and clay) and use them to identify their soil type. They will gather a soil sample from the Wildlands and use a soil chart to identify the soil type. Students will also estimate the percentage of different soil groups found in their sample by constructing a soil column. Data will be recorded online.

Grade Levels: 4-8 (Note: This experiment can be simplified or made more challenging depending on the developmental levels of your students. See Teacher Information.)

Approximate Time Involved: 1 - 30-minute session to learn about the basic types of soil, 1 - 30-minute classroom planning sessions, 20 minutes to collect soil samples, 20 minutes to classify soil types, 20 minutes to do the soil column test, 1-2 - 30-minute classroom sessions to examine results, state conclusions, draw inferences, and make recommendations, 20 minutes to enter data online,.

National Science Standards Addressed:

Content Standard A: As a result of activities in grades K-12, all students should develop

Abilities necessary to do scientific inquiry
Understanding about scientific inquiry

Content Standard C: As a result of activities, all students should develop understanding of:

(K-4) Organisms and environments
(5-8) Structure and function in living things
(5-8) Populations and ecosystems

Content Standard D: As a result of activities, all students should develop understanding of:

(K-4) Properties of earth materials
(5-8) Structure of the earth system

Program Standard D: The K-12 science program must give students access to appropriate and sufficient resources, including quality teachers, time, materials, and equipment, adequate and safe space, and the community.

Good science programs require access to the world beyond the classroom.

Teacher Information:

When students hear the expression soil, they think of dirt. Students first need to become familiar with different groups of soil. The most basic way to classify soil is by texture. Soil particles can be fine, medium, or coarse. Students will learn about the three groups of soil (sand, silt, and clay). Sand particles are large and coarse. Silt has medium-coarse particles. Clay is composed of fine particles. After learning about the different groups of soil students will determine what specific types of soil can be found in the Wildlands by using a soil classification chart. The amount of sand, silt, and clay ultimately makes up the type of the soil. To help better determine the type of an unknown soil students can calculate the percentage of sand, silt, and clay particles in a specific volume of soil. Soil particles are categorized into groups according to size.

Clay = less than 0.002 mm
Silt = 0.002 to 0.06 mm
Sand = 0.06 to 2.0 mm
Gravel = greater than 2.0 mm.

PERCENTAGES OF EACH GROUP FOUND IN DIFFERENT SOIL TYPES:

Sands: Soil that contains 85% to 90% or higher sand, with no more than 10% clay and with the rest silt.
Loamy Sands: Soil that contains between 70% to 85% sand and with clay being 14% or below.
Sandy Loams: Soil with 52% or more sand and 20% or less clay.
Loam: Soil with 7% to 27% clay, 28% to 50% silt, and less than 52% sand.
Silt Loam: Soil that contains 50% or more silt and 12% to 27% clay, or 50% to 80% silt and less than 12% clay.
Clay Loam: Soil that contains 27% to 40% clay and 20% to 45% sand.

Challenging Your Students to Be Problem Solvers:

To make this experiment more challenging to your students, you might want to pose questions such as: Conduct an experiment to determine if the soil type is the same at the north, south, east, and west ends of the Wildlands? Which area in the Wildlands would be the best place to plant a garden? Is the soil type at the top of a hill the same as at the bottom of the hill? Design and conduct an experiment to determine if the soil in various locations in the Wildlands differs. Design and conduct an experiment to determine if soil types change as you dig deeper into the soil.

This should become a team exercise where your student groups might each develop and write a hypothesis, list the materials they would use, the number of each item, and a procedure. An excellent way to assess this activity is to have the teams repeat each other's experiment to see if they achieve the same results. This will also replicate the real world challenges facing a research scientist.

Needed Materials: (Optional materials needed only if you wish to demonstrate the three distinct soil types: 100 ml. coarse sand, 100 ml. clay, 100 ml. silt). Per group: 1 - 6-8 oz. baby food jar or 100 ml. graduated cylinder (You will be looking at percentages so jar or cylinder size is not critical), 1 - container of water (or access to sink), 1 - hand spade, garden gloves, 1-2 - Ziploc plastic bags, (optional 100 ml. of a 5% Calgon solution*), 3 - different colored crayons. (NOTE: 100 ml. graduated cylinder or other ml. measurement devise will still be needed, but can be shared.)

*To make approximately 100 ml of a 5% Calgon solution, dissolve 5 ml. of Calgon in 95 ml. of water. Calgon is used as a precipitating agent to help the soil types to separate and settle faster.

Safety Rule: Students should always wash their hands upon completion of the experiment.

Procedure:

Student Information: The following information will provide you with the steps for setting up your soil experiment. It is important to hold all of the variables constant except for those that are being manipulated. Constant (or controlled variables) would be such things as: the percentage of soil, the percentage of water, and the depth at which the sample was taken. Manipulated (or independent) variables would be those things that we change to see if the response will be different, such as: the location where the soil sample is taken. The responding (or dependent) variable for this experiment will be the types of soil that you find in the different locations in the Wildlands.

Procedural Steps for Conducting the Investigation

(Optional Activity)

1. Your group will be given these materials: 3 types of soil, a baby food jar, a ruler, a graduated cylinder, and a water container.

2. Observe the differences between the three types of soil that you are given. Do this by placing a pinch of soil in the palm of your hand and adding a few drops of water to feel the difference in textures. Feel each of the three soil types. Sand-feels gritty & loose, silt-feels basically smooth (some grit) & sticky, clay-feels smooth & will form a ribbon when pressed between your fingers.

3. Add 10 ml. of silt to the baby food jar, followed by 10 ml. of clay and 10 ml. of sand.

4. Fill the baby food jar up with water, shake it, and let the soil settle.

5. When the soil has settled discuss how the soil has layered in the jar (sand at the bottom, silt in the middle, then clay at the top). Discuss the different properties of each type of soil. After this lesson you will be able to use this information to help you identify the soil you collect in the Wildlands.

Soil Type Experiment

1. NOTE: To help clarify the amount and variety of data you may want to collect, create a data table before beginning the experiment.

2. Your group will need these materials: Ziploc plastic bag, hand spade, container of water, graduated cylinder or baby food jar, and garden gloves.

3. Go to your chosen soil collection area and remove the vegetation from a circular area about 10 cm. in diameter (the size of a large hamburger bun). See photo below.

4. Once the vegetation is removed, collect enough soil in a Ziploc bag to fill your 100 ml. graduated cylinder or baby food jar. Try to keep the soil as fine as possible, making sure to remove worms and other insects or debris.
5. Bring soil samples inside or to a designated work area. Use no more than half of each sample to try to determine the soil types using the methods listed on the Soil Type Classification Chart at the end of this lesson. Below is a picture of how to create a soil ribbon.

6. Fill your graduated cylinder or baby food jar half full of soil from your Ziploc bag.

7. Fill the graduated cylinder or jar with the Calgon solution or plain water. Stopper the cylinder or hand tighten the lid onto the baby food jar. Repeatedly turn the container upside down and right side up for about twenty-five seconds. Let it settle for twenty-four hours. Below is a picture of a soil/water solution that has settled for about five minutes.

8. Make your observations and determine the percentage of each soil type.

9a. If you used a 100 ml. graduated cylinder, then the percentage can be determined by taking the number of ml. each layer takes up and dividing it by the total number of milliliters of soil. (NOTE: The total amount of soil will probably be less than 50 ml. because of air spaces in the original amount that have now been replaced by water.) Ex. 45 ml. of soil/ 10 ml. of sand = 22%

9b. If you used a baby food jar, then you must mark the level of each layer on the side of the jar with a crayon. Use a different color to mark each layer. Pour out your soil column and then using a graduated cylinder or ml. measurement instrument, carefully full your jar to each line with water and record the number of milliliters that each section represents. The percentage can be determined by taking the number of ml. each layer takes up and dividing it by the total number of milliliters of soil. (NOTE: The total amount of soil will probably be less than half of the baby food jar because of air spaces in the original amount that have now been replaced by water.) Ex. 70 ml. of soil/ 10 ml. of clay = 14%

10. Compare your soil samples and results with other groups.

Below is a list of questions that can be used to stimulate student discussions. If your students are at a developmental level where you are able to challenge their higher level thinking skills, then only present them with the first set of questions from each group below. Use the second list of questions as a way to stimulate thinking when your students seem unable to expand their knowledge on their own.

Examining Local Results

Discussion Questions that Require More Critical Thinking Skills:

What were your conclusions for this experiment?
What could you infer based on your conclusions?
How would you design this experiment differently the next time?

Discussion Questions that Require Less Critical Thinking Skills

What types of soil did you find?
What other types of soil were found in the Wildlands?
What might be the reasons for some groups finding different types of soil?
What soil groups did you find in your soil sample?
Do you think if you dig deeper you will have the same soil type?
Would the area of your soil sample collection be a good place to plant flowers? A garden?
What things might be done to change the soil types found in the Wildlands?

Examining Results

Discussion Questions That Will Require Critical Thinking Skills to Compare Local Data to the Online Data of Others

How did your results compare with the results of others?
What conclusions can you make when you compare your results with the results of others?
What inferences can you draw from your additional conclusions?
What changes would you now make in this experiment based on the information you now have?

Soil Links

University of Illinois Extention A great game for students! Help the detective dig up clues and learn about soil.

Soils of Arid Regions of the U.S. and Israel This site provides excellent ideas for expanding your students' knowledge of soil.

Field Museum Underground Adventure Exhibit at the Field Museum of Natural History, Chicago, IL.

Soil Investigation Here are some activities that you might want to look into.