Soil and Rocks Teacher Guide

Unit

Soil and Rocks

Subject

Earth and Space Science

Grade Level

ES 5-6

Activity Name(s)

Crystals

Introducing Soil

Weathering Rocks

Being Prepared

For both of these activities teachers may want to do pre-teaching on how to use microscopes.

Crystals

Arrangement: Students should be placed in small groups around the microscopes. The students will also need goggles due to the Borax mixture. The teacher will need to have cut out enough squares and equilateral triangles so that students can cover their desks and the students will also need a location for the jars to that will not be disturbed. **This activity will take several class periods.**

Introducing Soil

Arrangement: Students should be placed in small groups around the microscopes. The teacher will need to gather soil samples from an outside location. The students can either place the soil samples on a tray or the desks/table can be covered with newspaper and the students will also need to wear gloves when handling the soil samples.

Weathering Rocks

Arrangement: Students should be placed in small groups around the microscope. The students need to wear goggle when dealing with the vinegar. The teacher also needs to go through the appropriate way to use the eye dropper (the size of the drops that they are expected to use).

Getting Started

Crystals

The item that is used to secure the string that the crystals will grow on needs to be longer than the width of the mouth of the container that is used.

The digital microscope needs to be set-up in a location that students will be able to easily access days later to finish the activity. This activity will take longer than one class period.

Suggested Timeline

Crystals - three to four days depending on crystal growth (class one 45 min. to 1 hour, classes 2 and 3 observing crystal growth, and class 4 taking 30 to 45 minutes).

Introducing Soil - 45 min. to one hour.

Weathering and Erosion - 45 min. to one hour

Thinking about the Discovery Questions

This unit is motivated by the discovery questions:

• How do crystals form?
• What are the different materials in soil?
• How do you think rocks are formed?

The Earth is made up of different living and nonliving materials. Elements form minerals and mineral form rocks. These rocks can be transformed through the Rock Cycle into Sedimentary, Metamorphic, and Igneous Rock types. Through the Rock Cycle the processes of weathering and erosion, rocks can change, break, and move. The mineral mix with organic material and soil is created. Plants and animals greatly depend on the mineral found in this soil.

Misconceptions

A misconception that students have are that rock can move. Students do not understand that the movement of rock through erosion and then deposition is instrumental to the formation of Sedimentary rock. They also struggle with the fact that a Sedimentary Rock can then be pushed down and heated as it gets closer to the mantle. When this happens Metamorphic rock is then created through heat and pressure. If crystals form in Metamorphic Rocks then they are tiny. If the same rock is then continued to be heated and liquefied Igneous Rock is then formed. This is where crystals are formed. These crystals are formed because pure substances come together as the rock slowly cools. The slower the cooling process occurs the larger the crystal formation that you will see. The students also have trouble understanding that soil is a pre-cursor of rock. Without soil rocks would not be able to form.

Learning Objectives

• NGSS
  • Performance Expectations
    • 4-ESS1-1. Identify evidence from patterns in rock formations and fossils in rock layers for changes in a landscape over time to support an explanation for changes in a landscape over time.
    • 4-ESS2-1. Make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation.
    • MS-ESS2-1. Develop a model to describe the cycling of Earth's materials and the flow of energy that drives this process.
    • MS-ESS2-3. Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
  • Disciplinary Core Ideas
    • ES-ESS1: Earth's Place in the Universe
      • ESS1.C: The History of Planet Earth
        • Local, regional, and global patterns of rock formations reveal changes over time due to earth forces, such as earthquakes. The presence and location of certain fossil types indicate the order in which rock layers were formed. (4-ESS1-1)
    • ES-ESS2: Earth's Systems
      • ESS2.A: Earth Materials and Systems
        • Rainfall helps to shape the land and affects the types of living things found in a region. Water, ice, wind, living organisms, and gravity break rocks, soils, and sediments into smaller particles and move them around. (4-ESS2-1)
      • ESS2.E: Biogeology
        • Living things affect the physical characteristics of their regions. (4-ESS2-1)
    • MS-ESS2: Earth's Systems
      • ESS2.A: Earth Materials and Systems
        • All Earth processes are the result of energy flowing and matter cycling within and among the planet’s systems. This energy is derived from the sun and Earth’s hot interior. The energy that flows and matter that cycles produce chemical and physical changes in Earth’s materials and living organisms. (MS-ESS2-1)
      • ESS2.B: Plate Tectonics and Large-Scale System Interactions
        • Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth’s plates have moved great distances, collided, and spread apart. (MS-ESS2-3)
  • Practices
    • Developing and using models
      • Develop and/or use a model to predict and/or describe phenomena.
    • Planning and carrying out investigations
      • Conduct an investigation and/or evaluate and/or revise the experimental design to produce data to serve as the basis for evidence that meet the goals of the investigation.
    • Analyzing and interpreting data
      • Analyze and interpret data to provide evidence for phenomena.
    • Constructing explanations and designing solutions
      • Construct an explanation that includes qualitative or quantitative relationships between variables that predict(s) and/or describe(s) phenomena.
      • Construct an explanation using models or representations.
      • Construct a scientific explanation based on valid and reliable evidence obtained from sources (including the students’ own experiments) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.
  • Cross Cutting Concepts
    • Patterns
      • Students recognize that macroscopic patterns are related to the nature of microscopic and atomic-level structure. They identify patterns in rates of change and other numerical relationships that provide information about natural and human designed systems. They use patterns to identify cause and effect relationships, and use graphs and charts to identify patterns in data.
    • Cause and effect
      • Students classify relationships as causal or correlational, and recognize that correlation does not necessarily imply causation. They use cause and effect relationships to predict phenomena in natural or designed systems. They also understand that phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.
    • Systems and system models
      • Students can understand that systems may interact with other systems; they may have sub-systems and be a part of larger complex systems. They can use models to represent systems and their interactions — such as inputs, processes and outputs — and energy, matter, and information flows within systems. They can also learn that models are limited in that they only represent certain aspects of the system under study.
    • Stability and change
      • Students explain stability and change in natural or designed systems by examining changes over time, and considering forces at different scales, including the atomic scale. Students learn changes in one part of a system might cause large changes in another part, systems in dynamic equilibrium are stable due to a balance of feedback mechanisms, and stability might be disturbed by either sudden events or gradual changes that accumulate over time.
• NSES
  • Earth and Space Science - Structure of the earth system
    • Landforms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion.
    • Some changes in the solid earth can be described as the "rock cycle." Old rocks at the earth's surface weather, forming sediments that are buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues.
    • 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.
  • Earth and Space - Earth's history
    • Fossils provide important evidence of how life and environmental conditions have changed.
  • Earth and Space - Properties of earth materials
    • Soils have properties of color and texture, capacity to retain water, and ability to support the growth of many kinds of plants, including those in our food supply.

Discussion: Setting the Stage

Crystals

• How do crystals form?

  They grew out of mineral-rich solutions. When solutions are completely saturated with mineral components, crystals can begin to form on the walls of a container, on other crystals, or even on particles of dust. They can grow quickly or slowly - or even stop - depending on changes in temperature and the concentration of the solution.

• Do you think all crystals are alike?

  No, a lot of crystals might seem to look alike at first glance, but what elements the crystal is made out of will make it a unique shape and color. Even the same element can make different crystals, though, based on conditions such as temperature, light, and what other elements are around.

• What do all crystals have in common?

  They have symmetry, shine, brittleness (they fracture along faults), and are slow-forming.

Introducing Soil

• What are the different materials in soil?

  Organic matter: anything that was living or is still living, plant and animal; Inorganic matter: rock fragments (sand, silt, and clay).

• Do all soil have the same types of materials in it?

  No, soil that was used for farming will have a higher amount of organic matter that used for building purposes.

• Is soil made out of microscopic material?

  Yes, soil contains microscopic organisms, rock fragments (clay), and plant material.

Weathering Rocks

• Are all rocks formed the same way?

  No, rocks are formed through different processes. Sedimentary rocks are formed when soil and other materials on Earth's surface are eroded and settled forming a layer of sediments. Over time these sediments are cemented together to form rock (sandstone, limestone, shale, etc.). Metamorphic rocks are formed when another form of rock is changed through extreme heat and pressure (marble, slate, schist, etc.). Igneous rocks are formed when melted rock cools and hardens. This melted rock can be found as either lava, when melted rock comes through the crust, or magma, melted rock found under the Earth's crust. Some examples are pumice, granite, obsidian, etc.

• How do you think rocks are formed?

  Rocks are formed by many different ways. Each type of rock is formed through a different process (Weathering and Erosion, Heat and Pressure, and Melting).

• Can you see the different particles that make up rocks?

  Yes, many sediments that are in sedimentary rocks are visible not only with the naked eye but also with the use of a microscope and/or hand lens. You can also see particles in the metamorphic rocks. You can usually see bands of different colors where the different types of rocks that have been pressed together and heated. Sometimes you can start to see crystalline structures starting to form, again you can use a hand lens and/or microscope along with the naked eye to see these particles. In igneous rocks you can see crystals that have formed during the cooling process, because of the melting of the rocks the materials are melted together and new rock is formed.

Discussion: Formative Questions

Crystals

• Do you think that crystal shapes are unique to a specific substance?

  No, there are basic crystal forms that minerals take. Each mineral will have one of these 6 so to some extent crystal shape can help with identification, eliminating some possibilities.

• What do all the crystals have in common?

  They are 3 dimensional and all that are made of the same material have the same shape.

Soils

• Will all soils have the same amounts of organic and inorganic materials?

  No, depending on where the sample was collected you may have more or less of each type of material. In a temperate forest with lots of trees you may find more organic material. On new soils forming on or near a volcano you may find little or no organic material.

• Would you say your sample has more organic or inorganic material in it?

  Answers will vary but students should provide evidence to support their ideas.

Weathering Rocks

• What are you seeing as you are looking at the different samples?

  Students should be seeing different particles depending on the sample. If they are looking at rocks then they should be able to see the particles that make up the rock sample. The particles are different depending on the type of rock. Sedimentary rocks have larger particles that can be seen (conglomerate) and smaller particles (sandstone) that can be seen either with the naked eye and/or microscope/hand lens. In metamorphic rocks students should be able to see some of the particles that make up the rock along with the development of tiny crystals. If the students are looking at an igneous rock sample then they could see smaller particles within the rocks (basalt and granite) or they will see holes where the rocks have cooled and air was trapped during cooling process (pumice and scoria). If they are looking at soil then they should be able to see sand particles, decaying plant parts, root hairs, insects, etc..).

Discussion: Wrapping Up

Crystals

• How do crystals form?

  They grow out of mineral-rich solutions. When solutions are completely saturated with mineral components crystals can begin to form on the walls of a container, on other crystals, or even on particles of dust. They can grow quickly or slowly - or even stop - depending on changes in temperature and the concentration of the solution.

Introducing Soil

• What materials are found in soil?

  Organic matter: anything that was living or is still living, plant and animal; Inorganic matter: rock fragments (sand, silt, and clay).

Weathering and Erosion

• How are rocks formed?

  Rocks are formed by many different ways. Each type of rock is formed through a different process (Weathering and Erosion, Heat and Pressure, and Melting). Sedimentary rocks are formed when soil and other materials on Earth's surface are eroded and settled forming a layer of sediments. Over time these sediments are cemented together to form rock (sandstone, limestone, shale, etc.). Metamorphic rocks are formed when another form of rock is changed through extreme heat and pressure (marble, slate, schist, etc.). Igneous rocks are formed when melted rock cools and hardens. This melted rock can be found as either lava, when melted rock comes through the crust, or magma, melted rock found under the Earth's crust. Some examples are pumice, granite, obsidian, etc.).

Additional Background

Crystals form out of mineral-rich solutions. When solutions are completely saturated with mineral components crystals can begin to form on the walls of a container, on other crystals, or even on particles of dust. They can grow quickly or slowly - or even stop - depending on changes in temperature and the concentration of the solution. Crystals might seem to look alike at first glance, but what elements the crystal is made out of will make it a unique shape and color. Even the same element can make different crystals, though, based on conditions such as temperature and light and what other elements are around.

Soil is a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment. The upper limit of soil is the boundary between soil and air, shallow water, live plants, or plant materials that have not begun to decompose. Areas are not considered to have soil if the surface is permanently covered by water too deep (typically more than 2.5 meters) for the growth of rooted plants. The lower boundary that separates soil from the nonsoil underneath is most difficult to define. Soil consists of horizons near the Earth's surface that, in contrast to the underlying parent material, have been altered by the interactions of climate, relief, and living organisms over time. Commonly, soil grades at its lower boundary to hard rock or to earthy materials virtually devoid of animals, roots, or other marks of biological activity. For purposes of classification, the lower boundary of soil is arbitrarily set at 200 cm. http://soils.usda.gov/education/facts/soil.html

Rocks are formed through different processes. Sedimentary rocks are formed when soil and other materials on Earth's surface are eroded and settled forming a layer of sediments. Over time these sediments are cemented together to form rock (sandstone, limestone, shale, etc.). Metamorphic rocks are formed when another form of rock is changed through extreme heat and pressure (marble, slate, schist, etc.). Igneous rocks are formed when melted rock cools and hardens. This melted rock can be found as either lava, when melted rock comes through the crust, or magma, melted rock found under the Earth's crust. Some examples are pumice, granite, obsidian, etc.

Analysis

Crystals

1. Compare the three samples you have studied. Describe what pattern you see in each case.

   Answers will vary depending on the samples. Students should provide evidence to support their answers.

2. Here are some pictures of rocks. What can you see that is evidence they are made from crystals? What size do you think the crystals are in each case?

   Sample A - The first one is quartz. It formed very slowly, deep within the earth. (The students will see very large crystals and a very small amount of rock material and the crystals are very large.

   Sample B - This one is granite. It also formed deep within the earth. Notice the different colored grains. (The students can see tiny shiny particles in the granite and the crystal sizes are small.)

   Sample C - This one is obsidian, which comes directly from a volcano. The molten rock is thrown into the air and crystallizes very quickly. (Obsidian is very shiny rock that is formed when molten rock cools quickly. This is what gives it its shiny appearance.)

3. Summarize your observations about crystals.

   Answers will vary based on observations, but should be supported with evidence.

Introducing Soil

1. Consider how your findings about soil quality might be influenced by the location from which the soil sample was taken. Did cut grass or leaves fall on it? Did people walk on it? Did machines drive on it?

   Students can observe if the soil is packed tightly that the soil was walked on repeatedly or driven on. Students can also see what organic material is located in the soil samples.

2. How do you think your soil sample compares with soil on Mars?

   Students should understand that the soil on Mars is much drier and has no moisture in the soil; therefore, Mars' soil is sandier than Earth's.

3. View each others samples and compare your findings. Who has the rockiest soil? the sandiest soil? the soil with the most organic material?

   Answers will vary depending on the soil samples, but should be supported with evidence.

4. Most plants like a mixture of organic and inorganic material, not too tightly packed. Do you think plants would do well in your soil? Explain why you think so.

   Answers will vary depending on the soil samples, but should be supported with evidence.

Weathering and Erosion

1. What kind of rocks do your samples appear to represent? What is your evidence?

   Answers will vary based on the samples that the students have. If the student has igneous rock then they will see the following: hard, dark, and fine grained; sometimes black and glassy, gray and white with air holes, and undistorted crystals, when cooled slowly. If the students have sedimentary rocks then the students will see the following: fossils, or holes and shapes where fossils once were, water or wind ripple marks, and easy to break. If the students have a sample of metamorphic rock then the students could see the following: glittery big crystals or distorted crystals (sometimes flattened); wavy layers, swirls, and twists; crystal holes, from where crystals have fallen out.

2. Did you observe any fizzing on the chalk and the rock when you added vinegar? Did this represent a chemical reaction? Be prepared to share your answers with the class!

   If the students have a sedimentary rock sample then they would observe fizzing and it is a chemical reaction.

3. How do you think the different types of rocks found in your area got there?

   Answers may vary, but may include weathering, erosion, and deposition.

4. What would you say to someone who says, "Oh rocks! They are all the same!"?

   No, all rocks are not the same. They are made our of different minerals and elements. They are also formed through different processes.

Further Investigation

Crystals

The students can create additional crystal structures using different material (table salt, sugar, rock salt, etc). Then the students can compare the crystal structures using a hand lens/microscope.

Introducing Soil

Students can research the proposed make-up of the terrestrial plants and compare their soil composition to that of Earth's.

Students can collect soil samples from several places around the school yard and compare their soil make-up.

Weathering and Erosion

Students can create an experiment that takes soil packed into a baking dish to see the erosion rate of soil. They can change the angle of their pans and the amount of water to see how much soil is eroded over a period of time by collecting the run-off and measuring the turbidity of the water by using a turbidity probe.