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Unit Goals: 1. Make science relevant to the student’s everyday life.
Show that science is everywhere.
Unit Objectives: The student will be able to:
Create a timeline of local geologic history
Create a local anthropological timeline
Describe and understand different soil profiles and horizons from different areas
Develop an understanding of the soil forming processes
Relate soil formation to climate
Describe how humans impact a given study site
Recognize any important mistakes made in the past that affect the environment for which we are paying today
Select, evaluate, and defend a stance on the local uses of soil (Farm land vs. Housing development)
Develop public speaking skills as well as skills in other disciplines

Target Population

The unit targets freshman-level high school students who live in or near areas of increased urbanization. A class size of twenty students allows sufficient time for in-depth debates.

Unit Length

The unit will be designed to last three to four weeks; however, the geologic timeline is a project that requires all year. The anthropological time line will also be an on going project. The actual time spent on the debates and researching the human impacts will be up to the students, if there is high interest, then longer time will be allotted.

Brief Geologic History

This unit assumes that the major portions of geologic history have already been covered. The main focus of this unit is the Quaternary Period. The Quaternary Period can be further divided into two epochs, Pleistocene, and Recent. The geologic history that is responsible for the majority of northern Illinois’ soil formation takes place during the Pleistocene, or Ice Age. During this time, massive sheets of ice descended from the north. The Keewatin Center, located in central Canada, was the source of the sheet of ice that covered much of north central United States (Spaulding & Namowitz, 1997). The massive ice sheets made four major advances and retreats on the northern United States during a million year time period of global warming and cooling. The final glacial maximum, around 22,000 to 14,000 years ago, developed from the Laurentide ice sheet (Merrits et al, 1998). During this time much of the mid-west was covered with ice. The last major glacier receded around 11,000 years ago.

The ice sheets not only scraped the landscape away, but it also scraped the bedrock and helped speed the physical weathering processes. The fine particles trapped in the ice sheets scraped and carved their way across the north central states and created some of the most fertile soils. A clear understanding of glacial action is required to set the foundations for comprehension of soil formation.

Soils are formed by the disintegration of rocks and minerals. As one can see, the climate is a major factor in soil development. Soils are very different from location to location. The soil basics that are outlined here are meant as an introduction to soil science. Soil is arranged in different layers and zones called profiles and horizons, respectively. The profiles can be thought of as the "big picture." This is what most people are familiar with seeing while passing a road cut or a construction site. The different layers of colored soil are what scientists call the soil profile. The horizons are the individual layers or "pieces" that make up the entire profile. The most common horizons, from the surface down, are the O horizon, A horizon, B horizon, and C horizon.

The O horizon can be found at the upper most part of the pedosphere. This horizon is composed of mostly decaying organic material, hence the name O horizon. This horizon is very dependent on moisture. Desert soils often lack an O horizon because the rate of decomposition differs between arid climates and moist climates.

The second horizon is the A horizon. This layer is also known as topsoil. This material is rich with organic material and in some locations is high in minerals. This location has high activity on both the biological and geological spectrum. Many animals and insects live and burrow in this horizon. The roots of many plants penetrate into this horizon seeking out the moisture and minerals that they need to sustain life. The geological activity is also busy. The formation of new soils between the O horizon and the A horizon is an exciting process. This is where new soil is being formed! Minerals from the A horizon leach into the next horizon, the B horizon.

At the B horizon, the materials are transported from the upper layers into this depositional horizon. In arid climates, one can find deposits of calcium carbonates (CaCO₃). These white, chalky, materials will effervesce when hydrochloric acid is introduced to their surfaces. As water percolates through the soil and encounters calcium carbonate, calcium hydrogencarbonate [Ca(HCO₃)₂] is formed. This substance is also known as hard water (Brimblecombe et al, 1998). The solution reaches certain areas of the soil where the water can no longer descend. As a result, the solution begins to form a deposit. As the water slowly evaporates, the calcium carbonate is left behind.

Finally, the boundary between the parent rock (bedrock) and the C horizon becomes less apparent. The C horizon usually contains highly weathered and fractured bedrock mixed with soil. The question then arises, is the soil formed from the bottom up, or from the top down? The soil conservation activity might give us some clues.

The basic knowledge of soil is the start of a wonderful journey into learning what is really going on inside the earth. We need to look and start at the surface because this is where all the sciences (Biology, Chemistry, Geology, Meteorology, and Physics) come together. A good link for more soil information is: http://www.esf.edu/pubprog/brochure/soilph/soilph.htm

Brief Anthropological History

The unit assumes that there is some prior knowledge of the evolution of humans from Australopithecus through Homo sapiens. This topic is covered when talking about the rise of mammals during the Cenozoic Era.

Agriculture has been an integral part of American history since the 16^th century, and prehistoric agriculture dates back another 1000 years. The environmental effects of agricultural activities are seen in the farmer’s progress. The more "advanced" humans become the more adverse are the effects on the environment. The roots of agriculture stem back thousands of years. The earliest human ancestors were hunter-gatherers, a cultural adaptation requiring nomadism. Following domestication of livestock, nomads followed the herd as it foraged the landscape for food. A more readily available food source enabled larger and more families, thereby supporting larger population growth. The innovation of crop cultivation provided an even more readily available, stable food source, enabling permanent settlements. Thus our first small "towns" began to form and the human population increased more. Increasing population, unfortunately, further increases stress on the environment.

One theory in cultural anthropology is that the early humans actually worked harder as farmers than as hunter-gatherers. The theory proposes that the people that are presently nomadic have more hours of free time and a stronger family. I would venture to say that the impacts the nomadic tribes have on the environment are significantly less than the traditional or modern farms. This does not mean that nomads were completely environmentally friendly; I just think that their stresses on the environment were less severe as compared to the stresses that "advanced" humans place on the environment.

As the ancient farms grew so did the human population. Taking a great leap in history through the scientific revolution (1650-1800) and the industrial revolution (1700’s-current?), the agricultural revolution targeted the temperate grasslands. In the temperate grassland, the farms create a surplus of grains and vegetables for the world population. Farming has negatively influenced the soils in the grassland. Molles, (1999) for example notes that, "prairie soils have lost as much as 35% to 40% of their organic matter in just 35 to 40 years of cultivation." Molles also wonders if the environment will be able to sustain the agricultural needs of the human population. It seems that the environment is "the one" who is losing here.

One of the largest sprawling megalopolis is around Chicago. The surrounding land was once rich prairie that had small localized farms. But as Chicago grew the people had to live somewhere. So they moved out of the city. As more and more people moved out, more and more land was taken for housing developments. The developers had no regard for the environment. Their only regard was for the all mighty dollar. Care was not taken for wetlands or valuable farmland. An interesting catch-22 was beginning that still exists today. If the developers build nice communities and nice roads, then people will move out of the city and into a nice suburb. If the developers build them too nice then everybody will see the nice roads, schools, and houses and subsequently want to move into the development. So as a result more developments are built, and more people move out of the city. The traffic then gets so bad, that the infrastructure can’t handle it. This in turn makes the people unhappy. Didn’t they move out to the suburbs to get away from all the traffic and to get away from the city?

The area around Chicago is growing incredibly fast. The population is reaching a critical point. Cement and asphalt, all to support Chicago’s growing population, are now covering the land that was once fertile grassland. Ground water and water tables are reaching critical levels of stress. Meanwhile, the global human population is increasing exponentially at a surprising rate. "Like all other species, humans compete for and use essential resources-air, water, food, and space" (Merrits et al. 1998). Wouldn’t some scientists argue that competition is what allows certain species to continue replication and other species to perish? As humans do we have the right to decide what species continue and which ones perish?

Unit Rationale

Because human activity in the area has increased over the past twenty to thirty years (possibly more), the unit will focus on what exactly the humans have been doing recently to impact the environment. The two major goals of my class are to make science relevant to the students and show them that science is everywhere. I think that by studying the area that the students live in and by looking at the historical geology of the area, the students will be able to see that science is all around them. The other aspect of teaching historical geology to the students is now they can see why the landscape looks like it does today, and what it will look like in the future. By looking at the geological history of the area we can then see how the anthropological history fits into the story. I will ask questions such as, why did people choose to live here instead of there, and what are the results of people farming this area, and not this one? I really want to make the students think about what kinds of things are going on and show them that this "stuff" directly relates to them.

Activities

The following section contains many step-by-step lesson plans and lesson plan ideas that will be used for this unit.

Localized Geologic timeline (on going)
This activity will be a project that starts with the formation of the earth and works forward from there.
Objectives: The Student Will Be Able To:
Create a timeline that shows significant events in geologic history
Explain the different divisions of geologic time
"Rebuild" local geologic history from the literature
Materials: Paper, colored pencils, geologic maps of local area, reference materials
Procedure: There can be a variety of ways for doing this activity. One method I have seen is by using register tape and making a time frame equal to a distance. I don’t think this would be effective for this activity. I think a whole class demonstration of geologic time would be effective for showing how great the time span has been from the formation of the earth to the present. Ideally the entire classroom would be the timeline. The line can span across all four walls (space permitting) with sections designated for each era, period, and any other designations. This timeline would not be to scale, so it should be made apparent to the students that 1 meter is not 1 billion years. (If a time/distance scale is used, much of the information about the present will have to be squeezed into an area that is about the thickness of a paper.) Then as the students work on different periods their work will be posted at or under the proper location. The students will find or draw pictures of items or themes that represent the units of time.

Modifications: This activity can be assigned to each individual student (meaning each student is responsible for each era) or individual time units can be assigned to groups. I prefer the group assignments because then the students can present or teach their time units to the rest of the class. The variety of ways the students develop their presentations will also make this activity interesting. For interdisciplinary activities, see the next activity.

This activity will be a project that starts when humans arrived in the local area. This activity is a continuation of the above activity. It can also stand by itself. This activity allows for interdisciplinary study between earth science and the local history.
Objectives: The Student Will Be Able To:
Create a timeline that shows significant events in the local history
Explain why each event is significant
Compile the information into the "grand scheme" of geologic history
Materials: Paper, colored pencils, reference materials from or a guest speaker from local historical society
Procedure: This activity is pretty straightforward. The students find significant events, explain why they are significant, and draw or find pictures to describe the events. They then fit these events onto a larger timeline of the geologic history. Although humans have been around for a relatively short amount of time, the impacts of their activity can be seen at a local level as well as a global level.
Modifications: This activity is not limited to the local scale; it can be carried out at the global scale as well. The students can find world events that span the history of humans and fit them onto a time scale. For ideas about ways to display time scale see the lesson above on the geologic time scale.

These activities are borrowed from an introductory soil course. They can found in "Introductory Soil Science." To avoid copyright laws, I am not going to reprint the lab activities. These activities are the "meat" of this unit. I will, however, summarize and describe the objectives of these lab activities.
Lab Names (the objectives and descriptions follow the lab names)
Soil Parent Materials: Develop an understanding of the soil formation process. This activity is very similar to the activity below called "Soils and Their Parents."
Soil Structure: Understand how soil structure relates to soil texture and understand other soil properties. In this activity the students test the soils for different densities, pore spaces, stability of soil aggregates, strength, and permeability.
Soil Water: Understand the energy relationships of water in soil and understand some of the factors associated with ground water contamination. This activity requires the students to find different capacities for water. The students investigate how water behaves in different soils through different types of calculations.
Soils and Landscapes: Observe the patterns of soils occurring on various landscapes and understand that the characteristics of soil can be predicted from location. This activity requires the students to go around to different landscapes and observe the different types of soils and see how they formed. Pictures can be substituted for field trips.
Soil Profile Characteristics: Understand the differences that exist between soils and understand how soil characteristics affect the suitability of different soils for various uses. Here the students experience first hand what a soil profile looks like and they observe the different horizons. This is an out-of-the-classroom-experience where the students get dirty and look at soil in the field.
Soil Conservation: Explain the differences between tolerable and excessive rates of soil loss and learn how to predict soil loss for a given area. The students read about soil conservation and then learn how to calculate soil loss for given areas. This activity involves math and is an eye opening experience to see how much soil we are losing and why we need to conserve.

Soils and Their Parents
This exploratory activity is designed to let the students "play with" soils and rocks. See the lab activity above called "Soil Parent Material."
Objectives: The Student Will Be Able To:
Identify major rock forming minerals (prior knowledge or activity)
Identify minerals in different soils
Trace the steps of weathering from parent rock to soil
Materials: Different types of soil, Different parent rocks, hand lenses, Soil color chart (if available), hydrochloric acid in eyedroppers, Mineral identification guide (if available), colored pencils
Procedure: This activity is meant to get the students’ hands dirty. They should play with different types of soils and look at different types of rocks. Each sample should be placed at different location around the classroom. The students should then make as many observations as possible about each type of soil and parent rock. Have them create a chart that helps them observe the samples. Possible categories could be any of the mineral identification criteria, a sketch of the sample, or any guesses they have about the parent rock. A quick review of minerals might be helpful.
Modifications: A neat demonstration would be to take a rock and smash it into pieces and keep smashing it until it is completely disintegrated. Then have the students pick up the pieces and make observations from the demolished rock (sedimentary rocks are ideal). For added theatrical effect, one can play the disco-funk song, "Pick Up the Pieces."

Soils Profiles and Soils Horizons
The students will create their own soil horizons and profiles of different areas, particularly areas of prairie soils, farmland soils, and urbanized soils. Objectives: The Student Will Be Able To:
Create a soil profile from different locations
Describe each horizon in the profile
Explain the significance of climate on soil formation
Materials: Clear two-liter bottles (3 for each profile), different soils, minerals, and rocks, cement, reference materials
Procedure: This activity requires some background investigation as to what soil really looks like. In order to accomplish this we must dig up soil, or find locations where the soil is exposed. Construction sites are ideal for exposed soil. The two-liter bottles must be cut so they can be stacked on top of each other so that one continuous profile can be made. This activity has three basic requirements: it must be 3-D (taken care of right of the bat), it must be realistic (to scale), and it will be orally presented to the instructor. The students will need to build the profile, horizon by horizon, from the bedrock up to the surface. Each group of students should construct their profiles and then they must verbally explain their profile to the instructor. During the explanation, the students should somehow relate climate to soil formation, and should be able to explain each horizon. This activity is great for incorporating the Multiple Intelligences Theory. It is great because it tests other intelligences (visual/spatial, verbal/linguistic, artistic) instead of the usual logical-mathematical model of assessment.
Modifications: The students might enjoy digging up different areas for an independent study on soils. This should be encouraged! This activity is a great opportunity for small field trips around the school or around the town; it all depends on school location. Other materials could be used instead of dirt; food for instance, might be a fun medium to use for demonstration purposes. Any other type of material could be used to hold the profile instead of the two-liter bottles. I like the bottles because they act almost like a "soil-core" sample.

Guest Speakers
Guest speakers give the students a chance to see that people have jobs in different fields of science. The guest speakers would come from a variety of sources. They should come from both sides of environmental arguments. For example, someone from Chemlawn (a company that sells "green" lawns) could speak to the students about the environmental impacts of their company. Then getting someone from a local environmental group to speak to the students about their findings regarding the impacts of Chemlawn. Then I would like the students to make their own informed decision.

Public Speaking
Debates about certain "controversial" issues.
Objectives: The Student Will Be Able To:
Select, evaluate, and defend a stance on the local uses of soil (Farm land vs. Housing development)
Develop an organized presentation on land uses and the resulting impacts
Follow the conventions of public speaking for a formal debate on assigned topics.
Materials: Library or Research time, posters boards, markers, PowerPoint (if available)
Procedures: This activity is highly student-centered. The students can work in groups or individually. The topics are at the teacher’s discretion. Some possible topics: Housing Developments vs. Farmland, Ground water usage by big corporations (Pro’s and Con’s), Public water usage vs. Private water usage, Organic Farming vs. Commercial Farming, or City Park construction (Pro’s and Con’s) just to name a few. The students should research the topic and debate the issue at hand. They should have visual aides as well as sound data. The students should respond well to these types of activities because they are forced to really care about the topic one way or another.
Modifications: The students could be presenting their information to an imaginary town planning committee, or any other imaginary group, possibly made up of other students in the class. Another possibility could be presenting the topics to another class, possibly younger students. The students not actively involved in the debate process could write a one-page response to the information being resented. This keeps all the students in the class involved rather than the ones who are doing the debating.

The students should also look around the school and see the impacts the school has on the environment. I would like to get the students out of the classroom as much as possible (so they can experience science first hand) to test the soils and describe what humans have done to the local (around the school) geology.

After looking around the school we would go out to the countryside to see what impacts farms and housing developments have on the environment. Here we would also test the soil color, soil pH, and run other simple tests around the area. Any activity designed to get the students out of the classroom and getting their hands dirty.

The unit requires the student to step out of the traditional classroom setting and explore the "real world." The form of assessment that I like to use is performance assessment. I think that having the students do something or make something and explain what they are doing and why they are doing it their way is what life is all about. The traditional forms of assessment, in my opinion, are obsolete in today’s society (maybe they were obsolete years ago too). Why not create assessment relevant to the students’ lives as well as the content?

Another type of assessment that I would like to try is have the students write a one page (no more) reaction paper to the activities, discussions, and debates that we had in class. I think that maybe one or two of these papers would be a really awesome way to see what is going through the student’s mind. The other great thing is there would essentially be no right or wrong answers, just better answers. By writing a reaction paper, students have to take ownership of the content and really explain the content and explain themselves, both higher order thinking skills. If I can get the students to take a stand, what better way to get them involved with the content and working to make changes in and around their community.

The debates would serve as a culminating activity for this unit. The students would then have a better understanding of what is really going on. I really don’t think any end-of-the-chapter test will give me those kinds of results. The reason I would like them to write a reaction paper is because the student chooses what he/she would like to write about instead of being forced to write about a given topic. The other way I would like to try the assignment would be give the students a list of different types questions to ask their parents, neighbors or other members of the community, questions designed to spark discussion. Then I would like the students to write about their reaction to the discussion. Of course there would be the traditional grading of labs and other activities, but this way is the best for me.

So how can I raise awareness in my students? I think that by having them take an active role in the environmental struggle between urbanization and agriculture, then they will be true environmental advocates.

If you have any questions or comments please feel free to email me at this address: Karlnracheld@msn.com