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The Dirt on Soil

Grades: 5-8
Author: Joyce Brumberger
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Abstract

Module Description

As a result of the presenter-conducted module, participants will learn about some of the properties of soil and factors that affect the ability of water to permeate through the soil to an aquifer. Participants will construct a model water treatment plant based on experimentation and research. Through design and implementation of their own experiments, participants will design a lesson they can implement in their own classroom.

Objectives

Participants will learn to identify physical properties of basic soil types
Participants will learn about porosity and permeability
Participants will learn about soil's ability and limitations to purify water that reaches an aquifer
Participants will learn how aquifers recharge
Participants will design and construct a model of a water treatment plant.
Participants will produce a lesson plan to guide their own students in the design and implementation of an experiment

Materials

Engagement:

Refer to Edible Dirt Recipe
Plastic teaspoons
Small plastic cups

Exploration:

Poster size writing paper and markers
Soil Exploration Worksheets
6 large plastic bins
Small shovels or scoops
2 L bottles - 1 set of 3 bottles with caps for each group and 1 set for demonstration table
1 L bottle or pouring container - 1 for each group
Scissors
Sandwich zip lock baggies
Magnifying glasses - 1 for each participant or set of partners.
Soil samples of sand, silt, and clay. "Play sand" can be purchased at a home improvement store in the garden section. Silt and clay can be purchased through a catalog company such as Ward's Natural Science (www.wardsci.com)
8 oz. or larger, clear plastic cups - 1 for each group
Water
100 mL graduated cylinder, 1 for each group
400 mL beakers, 1 set of 3 for each group
Ring stands - 1 set of 3 for each group and 1 set for demonstration table
Ring clamps - 1 set of 3 for each group and 1 set for demonstration table
Stopwatch - 1 for each group
Paper towels
Landscaping marble chips - enough to fill a 2 L bottle 1/3 full.
Pebbles - enough to fill a 2 L bottle 1/3 full. Marble chips and pebbles can be purchased in the garden section of a home improvement store.
Aquarium gravel - enough to fill a 2 L bottle 1/3 full. Aquarium gravel can be purchased at a pet store or in the pet section of Walmart, K-Mart, or Target.
Soil sample from backyard or other source
Screen mesh (cut into 3"x 3" squares) - can be purchased in lengths at a home improvement store where screen is used to repair screen windows
Craft sticks for stirring
White paper or card stock
Food color dropping bottles, one for each group
Film canisters or condiment cups - 1 per group
Alum (about 8 oz.) - can be purchased at the local pharmacy. Ask the pharmacist as it is stored behind the pharmacy desk
Activated charcoal (l bag) - This can be purchased at the same stores as aquarium gravel.
Computer to show downloaded video from the Internet
Dropping bottles containing diluted bleach solution (used to simulate chlorine in water treatment plant)

Procedures

Engagement

The professional development provider welcomes participants to class and begins taking attendance. While doing so, she interrupts herself by saying that she is really hungry and needs to eat. With that, she begins dramatically searching for a spoon, previously placed somewhere, all the while lamenting of her hunger. She then approaches a potted flower sitting on a desk or window sill. She picks it up and begins eating the "dirt" (see preparation instructions) reveling in how delicious it is. She responds to the comments of shock and surprise of participants and invites them to have some "dirt" too. She scoops out "dirt" into small cups and provides spoons for all to share. (This could be prepared ahead of time and placed out of sight.)

Assessment: Assessment is ongoing as participants respond orally during the Engagement phase.

Exploration

Part I

Instruct participants to brainstorm individually about everything and anything they know about soil and record.
Invite them to get into groups of 4 and share their ideas to create a collective list.
Ask one participant from each group to share the knowledge of the group and record all on poster size paper. Hang the papers on the wall to be referred to during the course of the lesson.
Provide each group magnifying glasses and three soil types: sand, silt, and clay. Instruct them to observe the physical properties of each and record on the worksheet.
For the texture test, have participants wet their forefinger by dipping in a small cup of water before feeling the dry soil sample.
Set up the three pre-prepared cut off soda bottles containing the marble chips, pebbles, and aquarium gravel on ring stands with the spout facing downward. Ask participants to indicate which bottle represents a particular soil type. Complete the soil column on the worksheet indicating particle size.
Ask participants in what way the model is similar to the soil and in what way(s) the model is different. Answers will vary, but it should be noted that the texture and color are different.

Part II

Instruct participants to brainstorm in their groups if particle size of soil has any important significance.
Ask one participant from each group to share the thoughts of the group and record all on poster size paper. Hang the paper on the wall to be referred to during the course of the lesson.
Ask another participant from each group to observe the three bins of "soil" particles and to draw a picture that illustrates the space between particles on the worksheet
Instruct the observer to return to the group to share his or her observations. All participants should then illustrate the particle space on their worksheets.
Instruct the groups to set up three rings stands with a ring holder and insert one cutoff 2 L bottle in each ring with the spout end down.
Instruct participants to put down a small plastic mesh in the bottom of the inverted bottle and insure that the cap is on securely, but not too tight.
Instruct participants to fill each soda bottle 1/3 full of soil; one soil type for each bottle. Be sure the levels are equal.
Instruct participants to place a 400 mL beaker under each bottle.
BEFORE adding the water, instruct participants to practice taking the bottle cap on and off. It is important to try and recap the bottle as quickly as possible.
In each group of 4 participants, one participant will be the time keeper; one participant will slowly pour 250 mL of water into the column of sand; one participant will slowly pour 250 mL of water into the column of silt; and one participant will slowly pour 250 mL of water into the column of clay. The participants will simultaneously pour the 250 mL of water into the three soil columns.
Instruct the timekeeper to announce when it is time for the three bottle caps to be removed. He or she will then start the stopwatch and announce time intervals such that the caps can be replaced at the one minute mark.
Instruct participants to measure the volume of water in each beaker by pouring the water into the graduated cylinder. This should be done for each beaker and emptied in a designated area before measuring the next beaker. Answers are recorded on the worksheet.
Ask a representative from each group to report the volumes of water obtained from each soil type and record on the board. Have participants find the average volume of water for each soil type based on all the data.
Instruct participants to empty bottles of soil into labeled plastic bins. Bottles should be wiped clean over the bins or garbage pail with a paper towel. DO NOT RINSE in sink. Clean work area.

Part III

Ask participants to brainstorm within their groups and have them illustrate on a large sheet of paper what they think a soil profile in nature would look like down to the bedrock.
Allow a representative from each group to discuss their profile with the whole class.
Ask participants in each group if soil can "clean" water. Have them support their answers with appropriate reasoning.
Provide each group with 250 mL of prepared "dirty" water in a clear plastic cup.
Instruct participants to stir the dirty water for 30 seconds and allow it to settle for 3 minutes. Instruct them to illustrate the contents of the jar after 3 minutes on their worksheet.
Ask each group to illustrate a soil column that would best cleanse the dirty water. Inform them that they may use more than one type of soil and that the column should represent what is found in nature. Accept all reasonable illustrations.
Instruct each group to put the plastic mesh at the bottom of each bottle and then add layers of soil, as determined by the group, until the bottle is 1/3 full.
Instruct participants to put a white card or sheet of paper behind the dirty water and rate its clarity from 1 to 5: 1 is clear, 5 is opaque. Record results.
Instruct participants to pour the dirty water into the soil column and allow it to flow through the column for three minutes into a clean beaker placed under the spout. Wipe the dirty water container clean and dry with a paper towel.
Instruct participants to cap the bottle and pour the water in the beaker back into the original "dirty water" container.
Instruct participants to rate the clarity of the water using white card or paper and the scaling system in step 8. Record results.
Ask participants to predict if the experiment was repeated with dirty water containing drops of food coloring if the soil would filter out the coloring. Tell them to record answers on the worksheet.
Instruct participants to repeat steps 9-ll with another sample of dirty water that has been tinted with food coloring. Record results.
Clean work area being sure not to dispose of soil down the sink.

Assessment: Assessment is ongoing as participants record and illustrate observations and ideas as well as respond orally during the Exploration phase.

Explanation

Ask participants to respond to the following questions:

Where does soil come from? Soil comes from the weathering of rock. Rock is weathered from sun, rain, ice, wind, running water, and other factors.
Describe the size, shape, and texture of each of the soil types. The sand particles were the largest and were the most angular. They felt gritty. The silt and clay were very small and their shapes were almost impossible to determine. They felt very soft and smooth.
What do the sizes and shapes of the different soil types tell you about how much they were weathered? Larger pieces are weathered less than the smaller ones and they have more angles. Smaller particles are more rounded, which indicates they were rolled and tumbled more and broke into smaller pieces.
What did you notice about the spaces between particles when observing the soil models of marble chips, pebbles, and aquarium gravel? The spaces between the marble chips looked larger than the aquarium gravel. The percentage of space in the total volume of the soil is called porosity.
What factors do you think would affect how well water could travel through soil? The size of the spaces between particles and how well the spaces are interconnected. If spaces are blocked than it will be more difficult for water to flow.
Which soil sample produced the least volume of water in one minute? Answers will likely be clay though silt may also produce the same volume of water based on the allotted time.
What might be a reason for the differences in permeability, rate at which the water flows through the soil, for the various soil types? The amount of space between the particles and how packed the spaces are. The smaller particles became more compacted when the water passed through them and reduced the connection between spaces.
Different plants need different types of soil to grow. If you had a plant that required a lot of water and you had a very sandy soil, what could you do to the soil to increase its ability to hold water? Mix the sand with some silt or clay so that the spaces between the sand particles would be smaller. It would require a little experimenting to determine how much silt or clay to use.
Can nature "clean" water? When dirty water percolated through the soil column it came out clearer than it was originally. When the red food coloring was added to the dirty water in the second experiment, the red dye came out with the water. Nature may be able to clean some water but there are other factors that have to be considered.
What did the red food coloring represent in the second "dirty water" experiment? The red dye represented chemicals and other contaminants that the soil could not filter out. Sometimes contaminates are in the soil and clean rainwater filtering through the contaminated soil picks up the contaminants and collects in the groundwater below.

Assessment: Assessment is ongoing as participants respond to questions and ask additional questions that clarify or validate their own understanding.

Elaboration

Prior to this section of the lesson, the professional development provider instructs participants to research the process by which water treatment plants process water for human consumption. Participants should be encouraged to bring written notes to the work session.
In the class session, the professional development provider plays the short video downloaded http://www.waterandwastewater.com/videos/view_video.php?viewkey=84325132fca8edcdfb40
Provide each group of participants with a bin of materials described in the Preparation for Elaboration section.
Based on the video and their research, instruct the groups that they are going to construct a model of a water treatment plant.
Instruct the participants of each group to collaborate and draw a diagram of the various steps in the water treatment process.
Instruct groups to look at the materials in the bin and tell them they must use all the materials provided.
Instruct them to indicate on their diagram where each of the provided materials will be used. (Refer to "Sample of creating a model water treatment plant" for some guidelines.)
Ask one representative of each group to share the diagram with the class a whole. Allow for positive interaction of the participants in discussing the sequence of steps.
Replay the video and allow groups to make final changes to their water treatment plant.
Provide each group with 250 mL of dirty water.
Instruct each group to build and test their water treatment plant.
Instruct participants to dispose of materials in the designated areas.

Assessment: Assessment is ongoing as participants record and illustrate observations and ideas as well as respond orally during the Elaboration phase

Rationale

As our nation becomes more cognizant of the environment, there is a greater effort today to go "green". To support that effort, it is important for individuals to be knowledgeable in how nature takes care of itself. Water is precious and the cycle by which it travels from the atmosphere, biosphere, and lithosphere impacts all life on Earth.

The focus of this lesson is to begin to look at water as it reaches the Earth's surface and how it collects in the layers below. It is these pockets of water that most populations depend for their drinking water and daily activities. Studying the natural flow of nature helps provide understanding so that man can use materials and technology in ways that reduces his impact on the environment - "going green".

Science Standards

NSES CONTENT STANDARD D: Earth and Space Science
As a result of their activities in grades 5-8, all students should develop an understanding of

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.

NSES CONTENT STANDARD E: Science and Technology
As a result of activities in grades 5-8, all students should develop an understanding of

Perfectly designed solutions do not exist. All technological solutions have trade-offs, such as safety, cost, efficiency, and appearance. Engineers often build in back-up systems to provide safety. Risk is part of living in a highly technological world. Reducing risk often results in new technology.
Technological designs have constraints. Some constraints are unavoidable, for example, properties of materials, or effects of weather and friction; other constraints limit choices in the design, for example, environmental protection, human safety, and aesthetics.
Technological solutions have intended benefits and unintended consequences. Some consequences can be predicted, others cannot.

NSES CONTENT STANDARD F: Science in Personal and Social Perspectives
As a result of activities in grades 5-8, all students should develop an understanding of

Natural environments may contain substances (for example, radon and lead) that are harmful to human beings. Maintaining environmental health involves establishing or monitoring quality standards related to use of soil, water, and air.
Human activities also can induce hazards through resource acquisition, urban growth, land-use decisions, and waste disposal. Such activities can accelerate many natural changes.
Technology influences society through its products and processes. Technology influences the quality of life and the ways people act and interact. Technological changes are often accompanied by social, political, and economic changes that can be beneficial or detrimental to individuals and to society. Social needs, attitudes, and values influence the direction of technological development.
Science cannot answer all questions and technology cannot solve all human problems or meet all human needs. Students should understand the difference between scientific and other questions. They should appreciate what science and technology can reasonably contribute to society and what they cannot do. For example, new technologies often will decrease some risks and increase others.

NSES PROFESSIONAL DEVELOPMENT STANDARD A: Professional development for teachers of science requires learning essential science content through the perspectives and methods of inquiry. Science learning experiences for teachers must:

Involve teachers in actively investigating phenomena that can be studied scientifically, interpreting results, and making sense of findings consistent with currently accepted scientific understanding.
Address issues, events, problems, or topics significant in science and of interest to participants.
Introduce teachers to scientific literature, media, and technological resources that expand their science knowledge and their ability to access further knowledge.
Build on the teacher's current science understanding, ability, and attitudes.
Incorporate ongoing reflection on the process and outcomes of understanding science through inquiry.
Encourage and support teachers in efforts to collaborate.

NSES PROFESSIONAL DEVELOPMENT STANDARD B: Professional development for teachers of science requires integrating knowledge of science, learning, pedagogy, and students; it also requires applying that knowledge to science teaching. Learning experiences for teachers of science must:

Connect and integrate all pertinent aspects of science and science education.

Best Teaching Practices

Inquiry
Learning Cycle
Science Process Skills

Time Frame

Engagement: 15 minutes; Exploration: 35 minutes each part (three parts); Elaboration: 60 minutes

Preparation

Prepare flower pot by following the directions for Edible Dirt.

Exploration

Empty soils into large plastic bins, one soil sample type per bin
Prepare sets of soil samples for each group by scooping soils into zip lock baggies and labeling. Each group should have a set containing sand, silt, and clay.
Remove 2-3 inches off the bottom of all 2-L soda bottles with a scissor.
Prepare 3 2-L soda bottles by inverting them spout side down into a ring clamp attached to a ring stand. Place a screen mesh piece at the bottom of each one and insure that the bottle caps are secure. Fill one bottle 1/3-1/2 full of marble chips. Repeat with the other two bottles, one containing small pebbles and the other aquarium gravel.
Soil quantities for each group's set of bottles can either be pre-bagged or representatives from each group can fill the bottles at a station containing bins of soil.
Fill one liter containers or pitchers with water, one for each group.
Prepare "dirty water" by filling an 8 oz. clear plastic cup 1/3 full of backyard dirt. Include leafy matter and small sticks. Fill the cup with water allowing one inch of space to remain at the top and add a craft stick for stirring.
Set up a station with containers where water filtered through the soil samples can be emptied.
Set up a station with 3 large bins where wet soil samples can be emptied and later dried.

Elaboration

Fill small containers with alum and label. Film canisters or condiment cups work well.
Prepare zip lock bags of sand for each group that would fill approximately 1/3 of a 2-L soda bottle.
Prepare zip lock bags of activated charcoal for each group that would fill 2" of a 2-L bottle.
Cut screen mesh into 3" x 3" squares
Prepare small dropping bottles of very dilute bleach that are labeled "decontaminant", one for each group.
Prepare "dirty" water samples as described above.
Prepare a box or bin for each group that contains the following:
1. Ring stand and ring clamp
2. Cut off 2-L bottle with cap
3. Small mesh screen for bottom of container
4. Small 3" x 3" screen mesh pieces for bottom of container and screening floating particles
5. Bag of sand
6. Bag of activated charcoal
7. Container of alum
8. Decontaminant dropping bottle
9. Plastic teaspoon
10. Dropping bottle of food coloring
11. White paper or stock card
12. Paper towels
13. 400 mL beaker
Set up station to empty sand and activated charcoal.

Safety

All soil samples can be collected in bins, dried, and reused.

Soil should not be washed down the sink drains.

Water can be disposed of outside.

Assessment

Assessments are ongoing throughout the learning cycle.

Teachers convert a teacher directed science activity into an inquiry based lesson plan for their students.

Explanation of Science

Soil is a result of the weathering of rocks. Different types of soil and the minerals they contain are a result of the type of rock from which they originated. The more the rock has been weathered, the smaller the particle size and the rounder the particle shape. A soil profile may contain a layer of organic material at the top. As the profile extends downward, particle size INCREASES. These materials are least weathered. Water permeates through soils at varying rates based on their porosity, the percentage of space between packed particles, and how those spaces are interconnected.

Eventually, water reaches the bedrock, which varies in depth from region to region, and begins to accumulate. This accumulation of water is called an aquifer. The layers of water with pore spaces filled with water is called the saturated layer and the region above where the pore spaces contain air is the unsaturated layer. The zone between the saturated and unsaturated layers is referred to as the water table. The water table fluctuates based on environmental conditions and human consumption.

Water quality of the aquifer varies based on the quality of the water that initially percolated through the soil, contaminates in the soil, as well as many other factors.

Handouts

Soil Exploration Worksheets

References:

Extensions

Research more about aquifers and build a model aquifer.

Research more about the factors that affect the weathering of rocks and design experiments to test the rates of weathering based on one or more factors.

Take a field trip to the local water treatment plant.

Experiment to determine the porosity and permeability of different soil types.

Research the main component of kitty litter. Find out where the major source of this material is found and other interesting ways this material is used. (Hint: the material is bentonite and 70% of the world's source of bentonite is found in Wyoming. It can also be purchased in health food stores as a colon cleanser.)

Use a soil testing kit to determine the ions in the soil such as phosphates and nitrates. LaMotte supplies many science catalog companies with kits of various types and prices.