GOAL:

To develop an understanding of the interdependence of all organisms and the need for conserving natural resources

The earth is a complex sphere composed of a variety of interdependent systems.

Ecology B2.00 To understand some factors that cause ecosystems to be different

2.01 examine the basic components of ecosystems.

2.02 examine the components of an aquatic ecosystem.

2.03 select a specific ecosystem found near the school and examine its components.

I. Examine the basic components of ecosystems
A. Conditions affecting an ecosystem
II. Examine the components of an aquatic ecosystem
A. Characteristics of a lake
B. Zonation of a lake
C. Temperature of a lake
D. Nutrients in a lake

COMPONENT OF SCIENCE: Process of Science

GOAL:

To enable students to demonstrate the processes of science by posing questions and investigating phenomena through language, methods and instruments of science.

1.3 COLLECTING DATA - The acquiring, recording, arranging and storing of information must be performed in a complete, accurate, concise and user-friendly manner.

1.3a Data are collected using the senses, instrumentation, and a variety of other technologies.

BENCHMARK: Multiple information sources are used to investigate phenomena.

1.3b Data should be appropriate, accurate, and free of bias.

BENCHMARK: Data collected during different experiments of common phenomena may be related.

TIME REQUIRED:

Five 50 minute class periods

Metric ruler, hand shovel, plastic sandwich bags, newspaper, tweezers, toothpicks, paper cups, thermometers, pointed stick, empty tuna-fish can, balance, soil, oven, large jar

Benthic zone, compensation depth, epilimnion, euphotic zone, eutrophic, humus, hypolimnion, limnetic zone, littoral zone, nutrients, oligotrophic, optimal temperature, 160; photosynthesis, precipitation, relative humidity, thermocline

This classroom connector addresses Instructional Objectives 2.01 and 2.03.

Have you ever wondered why you live where you do? (response) Give me some reasons why you live where you do. (student response) (List these reasons on the chalkboard. Look for reasons like 'this is where my parents work' and 'we like the climate' etc.) 160;

We are going to explore the reasons why living things have an address.

(Each day take a section of the content and then do the student activity that goes with it. Allow enough time to complete one activity per day. Be sure to retain the collected data so students can compare results. At the beginning of this strand, divide students into groups to work together on each activity. Students should work in the same groups each day, and if possible, in the same area on each activity. If it is convenient to use school grounds, do so. Use small areas of as many different sites as you can. If it is inconvenient to use school grounds, check with a state park or a nearby farm. All materials taken from the soil as well as the soil itself should be returned to the area from which they were taken.)

(After all content and activities have been completed, each group of students should be able to write a good profile of their small area. They have collected information about living things, soil, water, temperature and other factors they have noticed. Be sure to have each group share information they have collected and have the class arrive at some consensus about these activities. They should also point out some possible errors or sources of error in these activities. They are not meant to be quantitative but rather qualitative in nature. These activities should give the students some idea of the basic components of an ecosystem. They can vary some of the techniques and study other ecosystems in the same ways. An extension of this activity would be to choose another ecosystem and perform these same tests.)

Why can some living things do well in a certain environment and others cannot? The reason is that it is a place they find livable. It has the physical conditions such as temperature, moisture, wind, light, and type of land to allow them to do their job best. Most living things are born with abilities that work only in certain conditions. However, just like us, many living things can tolerate physical conditions that are not the best all  the time. Let's find out about the conditions. (Active Participation - Living things in the soil)

Many living things can function within a range of temperatures. The middle of the range is the best temperature. The best temperature is called the optimal temperature. Temperature and moisture are responsible for a green climate. Too high above, or too far below, the optimal temperature can cause living things to die.

Cold-blooded animals can not control their body temperature so they must live within a narrower temperature range than animals that can control their body temperature. In northern climates many warm-blooded birds and mammals are active when cold-blooded amphibians and reptiles must hibernate. (Active Participation - 'Measuring temperature of the soil')

How much water and the form it is available to living things is important. Too much as well as too little water can be harmful to living things. Can you name some forms of moisture? (response)

Precipitation is a form of moisture. Rain, sleet, snow, and hail are all forms of precipitation. Precipitation usually supplies most of the water needed by living things. This water collects in many different places. A large amount of it becomes part of the soil. The runoff water forms streams, ponds, lakes, and rivers. (Active Participation - "Measuring Water in the Soil")

Humidity is another form of moisture. It is the water vapor in the air. When you watch TV the weather person usually gives the temperature and then the relative humidity. When it is raining or snowing the relative humidity is usually 100. This means the air holds all the water vapor it can hold at the given temperature.

The water vapor comes from large bodies of water such as oceans, seas, or lakes. If the air containing the water vapor is cooled enough as it moves over land, the precipitation will fall.

Air movement caused by differences in air temperature is called wind. Wind is important to living things. It moves air causing precipitation, spreads pollen, seeds and spores of many plants. It causes evaporation of water from soil. It can blow away valuable top soil from land.

Light is another physical condition of the environment that is very important to all living things. The amount of light and how long it is present is very important to living things. Green plants need a certain amount of light every day to make food. Different plants need different amounts of light to produce food.

Plants grow toward the light. Animals depend on light to guide them. Light direction is important to migrating animals. Many use the length of daylight to tell them the time of year. The amount of light can cause them to migrate or grow heavier or different colored coats.

The type of land consists of the type of soil, elevation and shape. The type of soil depends on the kind of bedrock from which it was formed and the size of the pieces. The amount of humus it contains and the water it holds are important.

True soil has three definite regions of material. These three regions are topsoil, subsoil, and bedrock. The topsoil contains any small pieces of bedrock. The smallest pieces are clay. The largest pieces are sand. In between the clay and sand are pieces called silt. Much humus is found in the topsoil. There are spaces in the soil filled with air and water. Many decomposers live in the topsoil as well as green plants. The subsoil is more lightly packed with larger pieces of bedrock and very little humus. The bedrock is made of a variety of minerals bound together to form rock. In the next activity you will examine the parts of soil. (Active Participation - Parts of Soil)

Choose a part of your yard at home and run these same tests. Collect and record your data. Write a report of your findings.

I asked you why living things do well in some environments and can not live in other areas. You have completed a series of activities that can answer this question. Who can tell me why? (they have the light, water, soil, and physical conditions they need to live.) Now you have discovered the basic components of ecosystems. What was the importance of our accuracy when collecting data? (it directly determines our conclusion we draw about the ecosystem we measured) What types of error could have occurred? (student responses will vary) How could that have effected/changed our conclusions? (responses will vary)

Problem: To determine the kinds and number of living things in a five cm square of soil.

Materials: (per team) metric ruler, hand shovel or butter knife, plastic sandwich bag, sheet of newspaper, forceps or tweezers, toothpick, paper cups.

Procedure:

1. Go to the area assigned to you by your teacher.

2. Using the metric ruler, measure a square of soil five cm wide and five cm long.

3. Using the shovel or knife, dig straight down into the soil along the boundaries of your area. Dig down about five cm.

4. Carefully lift the square of soil into the plastic bag. Return to your work area or classroom.

5. Spread out the sheet of newspaper. Then remove the sample of soil from the plastic bag and gently place it on one side of the newspaper.

6. Take the sample apart. Count and list each living thing you find. For example, count every plant, ant, beetle, earthworm, etc., and list them on the data chart.

7. Use the paper cups to hold the different animals. Place plants and soil on the other side of the newspaper.

8. Count your living things and record in the data table. Write the name and number of each different living thing.

9. When you finish counting and recording, return all soil and living things to the area where you found them.

Data:

Total number of living things _______________

Enrichment:

Suppose you took ten samples from this same area. What would be the total number of each living thing you would expect to find?

Compare your data with other teams. How does their data compare with yours? Explain.

Problem: To measure the temperature of the soil.

Materials: Thermometer (O -100 C), metric ruler, pointed stick or sharpened pencil.

Procedure:

1. Measure a five cm x three cm square of soil close to the square used in Active Participation - Living Things in the Soil.

2. Lay the thermometer on the surface of the soil so that the bulb is on one corner of the square. Shade the thermometer from the sun and leave it in that position for five minutes. Record the temperature on data table.

3. Find and record the temperature for the other three corners and the middle of the square.

4. Measure five cm from the top of the pointed stick or pencil and place a mark.

5. Push the pencil into the soil until the mark on the pencil is reached. Pull the stick or pencil out of the soil. Do not allow the hole to collapse.

6. Carefully slide the thermometer into the hole. Again, allow the thermometer to remain for five minutes. Take the thermometer out and record the temperature.

7. Make a hole five cm deep in each of the other corners and the center of the square.

Data:

Surface of Soil Location Temp Corner 1__ Corner 2 __ Corner 3 __ Corner 4__ Middle____ Avg. Temp.____

5 cm Below Surface Location Temp Corner 1___ Corner 2___ Corner 3__ Corner 4__ Middle____ Avg. Temp.____

Conclusions:
1. What was the difference between the average surface temperature and the average five cm below surface temperature?

2. What was the reason for this difference?

3. If you took a reading at another time of day would you expect a difference in temperature? Why?

4. Which temperature would you expect to change: the surface or below the surface or both?

Problem: To measure the amount of water soil contains

Materials: Empty tuna-fish can, balance, small plastic bag, soil, oven, shovel.

Procedure:

1. Return to the same area you have been using to do activities.

2. Fill the plastic bag with soil from this area but do not include any plants. Do not dig deeper than five cm. Return to your classroom to work.

3. Using the balance, weigh the empty can. Record the weight in the data table.

4. Weigh out 30 grams of soil and place in the can.

5. Place the can in the oven, set at 100 degrees Fahrenheit for five hours until the soil is dry.

6. Weigh the can with the dry soil in it. Subtract the weight of the can from this measurement. This is the weight of dry soil. Record in the data table.

7. Subtract the weight of the dry soil from original weight of soil. This is the weight of the water. Record.

8. Divide the weight of the water by the weight of the undried soil. Multiply the answer by 100. This final answer is the percentage of water in the soil.

Data:
Water Content of Soil

Weight of can __grams

Weight-of original soil __grams

Weight of dry soil __grams

Weight of water __grams

Percent of water in soil ___%

Conclusions:
1. How does the weight of dry soil compare with your classmates?

More

Less

Same

2. How does your percentage of water compare?

More

Less

Same

3. Class data: How many percents were in the 35-45% range?

How many were below 35%? How many were above 45%?

4. How can you account for differences in water in the soil?

Problem: To separate soil into its parts

Materials: (per team) soil from previously sampled area, large canning jar, small plastic bag, small shovel, sheet of newspaper

Procedure:

1. Return to the area where you have been working.

2. Fill the plastic bag with soil from the area. Dig no deeper than five cm. Try not to include any plants. Return to your classroom to work.

3. Fill the jar two thirds full of water.

4. Spread the soil on the sheet of newspaper. Remove any large plant material and stones larger than a pea.

5. Pour the soil into the jar of water until the jar is one half full of soil.

6. Cap the bottle tightly and shake it for about 30 seconds.

7. Allow the soil to settle completely.

8. After the soil has settled, place the ruler alongside of the jar. Measure, from top to bottom, the thickness of each layer. Anything floating on the top can be called a layer. Record measurements on the data table.

Data:
Layers of Soil

Layer 1____mm
Layer 2____mm
Layer 3____mm
Layer 4____mm
Layer 5____mm

1. How does the thickness of your layers of soil compare with data of other students?

thicker__

thinner__

same __

2. The ability of soil to hold water depends on the amount of materials from each layer. Check your data on the activity in which you determined percentage of water in the soil. (For students with the highest percentage, what were their thickest layers?)

To view the classroom connector which addresses Instructional Objective 2.02, please click Ecology B2a

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This is the time this file has been accessed since 11/16/96.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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