The Dirtmeister is your personal guide to hands-on science exploration in the classroom. By participating in Dirtmeister's Science Labs, kids have the opportunity to experience science firsthand. The steps in completing the challenge follow the same methodology used by scientists in solving problems. After reading the question, students are encouraged to formulate hypotheses. With science expert Steve Tomecek (the "Dirtmeister") serving as facilitator, students complete the hands-on investigation and check their results against their predictions.

This month, we explore ecosystems in nature by making two mini-ecosystems in the classroom. Ecology is the study of life-forms and how they interact with each other and the surrounding physical environment. In most ecosystems, organisms provide one of three main functions. Producers such as green plants take energy from the sun and turn it into a form that they can use. (In the case of some marine ecosystems, producers take energy from chemicals inside the earth.) Consumers eat producers and, in turn, gain the energy that they have "fixed" from nonliving sources. When organisms die, decomposers help break down their tissues, returning some of the nutrients to the environment where they can be recycled into new life-forms.

In most ecosystems, the relationships between producers, consumers, and decomposers can get quite complex, with many different organisms interacting with each other. In addition, abiotic (nonliving) factors such as the availability of sunlight, water, and minerals can have major effects on the entire system. In this particular experiment, we've tried to make the ecosystem as simple as possible: the producers are the grass and other plants; the consumers are mostly insects and worms; and the decomposers are microscopic bacteria and fungi. If you were to simply let the ecosystem go, only providing it with water on a regular basis, you would see that as the plants matured, different populations of organisms would erupt. The key is that as a change happens in one part of an ecosystem, there is a corresponding response by all the other organisms that are present.

One of the major problems in natural ecosystems is predicting what will happen when synthetic or "unnatural" chemicals are introduced. In many cases, elements like pesticides are harmful to an ecosystem - although they were originally designed to be beneficial. Introducing them into an ecosystem often sets off a chain reaction of events that devastates the entire system. In the case of industrial pollution like acid rain, the problem is even worse, causing widespread destruction over a large geographic region.

This Dirtmeister's Science Lab on ecosystems helps students meet the following science-content standards as set forth by the National Research Council of the National Academy of Sciences:

• Students conduct a simple investigation. (Content Standard A)
• Students employ simple equipment and tools to gather data and extend the senses. (Content Standard A)
• Students use data to construct a reasonable explanation of how an ecosystem works. (Content Standard A)
• Students communicate investigations and explanations. (Content Standard A)
• Students discover that all animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants. (Content Standard C)
• Students discover that all organisms cause changes in the environment in which they live. Some of these changes are beneficial and some are detrimental. (Content Standard C)
• Humans depend on their natural and constructed environments. Humans change environments in ways that can be beneficial or detrimental for themselves and other organisms. (Content Standard C)
• Changes in environments can be natural or influenced by humans. Some changes are good, some are bad. Pollution is a change in the environment that can influence the health, survival, or activities of organisms. (Content Standard F)

Classroom management is always a critical factor for any successful lesson, and the Dirtmeister's Science Lab is no exception. The following strategies will help to maximize the use of the activity in various classroom situations:

While younger students (grades 1–2) should have no problem setting up the ecosystems, they may have problems making the observations and recording changes. Instead of writing their observations, they can draw what they see each day. This way they will have a pictorial log showing the changes in the ecosystem over two weeks.

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Extensions
Here are some suggestions to enhance the experience of Dirtmeister's Science Lab for your students:

Extensions on Ecosystems

• Have the class make a list of all the different ecosystems that they can think of, such as ponds, forest, jungles, grasslands, and oceans. What are some of the animals and plants present in each ecosystem? How do they connect with each other?
• Have the class research one particular ecosystem and play a "web of life game." Begin by writing on separate index cards the names of some animals and plants found in that ecosystem. Then write down on index cards the abiotic factors like rain, sun, soil, and air. Give one card to each student and have them sit in a big circle. Take a long ball of string and, starting with the student with the "sun" index card, have each student pass the ball of string on to another student to whom they are connected in the ecosystem. For example: The sun connects to the tree, the tree connects to a bird, the bird connects to a worm, and the worm connects to the soil, which connects back to the tree. Pretty soon you will have a massive spider web showing the interconnected nature of an ecosystem.
• Take a trip to a local ecosystem outside the school. It can be anything from a woodlot to the weeds growing between the cracks in a sidewalk. Have the students identify each of the organisms and its role in the ecosystem. Back in the classroom, have the students make a map of the ecosystem.
• Talk with your school librarian about researching ecosystems in the library using books and multimedia resources. (See Section 8 below.)
• Have the class use the computer to search the Web for supplementary articles on pollutants and the environmental damage they cause in various ecosystems.

General Extensions

Grades K-2:

• Provide space on a classroom bulletin board for the Dirtmeister's Science Lab. Assign different teams of students the task of designing the board and changing the postings to reflect the different Science Lab topics throughout the year.

Grades 3-5:

• Using computer software such as ClarisWorks� or Microsoft Works�, have students create and maintain electronic science journals. Encourage students to illustrate their work by using drawing or painting features of the software. This is an excellent way to keep notes and store the labs for future use.
• Have each student write an article about their favorite science experiment. Compile the articles into a science newsletter. If your class already publishes a monthly newsletter, feature a science topic in each issue, rotating the responsibility of writing the articles throughout the class.

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Resources
The following Scholastic supplemental materials can be used in conjunction with Dirtmeister's Science Lab.

• Big Books: Science (Grades K-4). This book series covers a variety of topics, from bugs to wind. They are brightly illustrated and great for the classroom library.

• Environmental Atlas of the United States, by Mark Mattson (Grade Levels 4 and up). The only environmental atlas for young readers that emphasizes U.S. ecological information.

• Be a Scientist skills books (Grades 3-6). This series includes featured scientists, hands-on activities, and an emphasis on practical process skills. The series consists of three sets of three books each for grades 3-4, 4-5, and 5-6.

• Super Science (Grades 3-6). High-interest articles and hands-on activities teach basic science and technology concepts. Each theme-based issue presents timely news and stimulates students' interest through fun activities. Exercises develop critical-thinking skills and help you meet the Natural Science Education Standards.

• Quick and Easy Learning Centers: Science, by Lynne Kepler (Grades 1-3). This Professional Resource book focuses on the use of everyday materials to promote independent, hands-on learning. Information on how-tos, management, experiments, and reproducibles are included in this helpful book.

Call Scholastic directly at 1-800-724-6527 to order and for more information.

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Related Web Sites

General Science Sites

Science and Technology for Children Curriculum
http://www.si.edu/nsrc/pubs/stc/overv.htm

The Natural History Museum (London)
http://www.nhm.ac.uk/index.html

Edison National Historic Site
http://www.nps.gov/edis/

Endangered Species Program
http://endangered.fws.gov/

National Inventors Hall of Fame
http://www.invent.org/book/index.html

Understanding Our Planet Through Chemistry
http://minerals.cr.usgs.gov/gips/aii-home.htm

Maps and References
http://www.cgrer.uiowa.edu/servers/servers_references.html

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