School Site Ecosystem Activity
Goal: To introduce students to the concept of ecosystem; specifically, the interrelationships among plants and animals within an ecosystem, and their relationships to the environment in which they live and interact.
Objectives: Students will demonstrate the ability to
Key Concepts: Each physical or biological change in the landscape of the earth initiates responses which determine the community of plants and animals that can occupy that landscape. All life functions within a web of interdependence, or ecosystem, and disturbance in one part of the web affects the whole ecosystem. Habitat disturbance causes change in species composition, affecting the rate and direction of succession.
- Define an ecosystem
- Examine a variety of plant specimens (stems and leaves) to determine the terminology which best describes their likenesses and differences
- Work cooperatively in groups to create dichotomous keys and practice their use
- Classify an assigned number of plant types found in easily-accessed ecosystems (near school or home)
- Record observations concerning soils, plants, and animals for three different accessible ecosystems
- Summarize major differences between three ecosystems.
Summary: Students are introduced to the concept of ecosystem, apply their new learning to examination of one disturbed and one undisturbed site near the school, and identify plants within each They categorize these plants and create a dichotomous key to be used in subsequent examination of three different ecosystems near the school. Students also record observations regarding numbers of plants observed in each study site, list animals and animal signs, and describe soils. Students participate in small group study of differences between ecosystems, and discussion of changes that might be expected, given continuation of current conditions.
Content Areas: Science (botany, biology), environmental studies
The following lessons are effective lead-ins to this lesson:
- Plant Identification Guide
- Plants of the Mount St. Helens Lahar - Key (as sample dichotomous key)
- School Site Ecosystem Observation Record
- Ecosystem Essay
- selected ecosystem plots near school
- Classification: A Life Skill
- Plants of the Mount St. Helens Lahar: Identification Activity
- Lahar Ecosystem Activity
Evaluation: Students will produce dichotomous keys for a group grade, and demonstrate individual learning by completing an essay test and self-evaluation of their learning.
- (Preparation) Before introducing students to this activity, locate an area near school, approximately 3-4 feet in diameter, where students have made a path by taking shortcuts or otherwise disturbed a natural or landscaped plot. Label this "Disturbed Area." Find and label another plot of similar size, "Undisturbed Area."
- (Part I) Explain to students that scientific investigation requires a curious, probing mind and the important skill of careful observation. Have students suggest, and cluster on the chalkboard, reasons why this is so.
- Ask students to imagine they are looking at a small plot of land, somewhere on the school grounds. Ask them to describe what sorts of things they might see; e.g., leaves, bugs, dirt, etc. Probe students' responses with questions that elicit further detail: Is the leaf oblong, oval, round? Does it have smooth edges or is it serrated like a steak knife? What is the dirt like: Sandy/loamy, soft/hard, dark/light? Cluster responses on the board.
- Discuss the importance of selecting words that precisely describe scientific observation. Elaborate the students' responses with descriptive adjectives and analogies.
- Divide class into learning teams of three students each. Explain that teams will practice their observational skills, approaching their study in the manner of scientists. Have teams visit both the disturbed and the undisturbed site, and collect from them stems with leaves of 6 to 10 of the plants common in each. Have each member of the team take one or two of the plants and examine them closely, recording his/her observations, and then reporting back to the group. The group should then develop a list showing characteristics of plants collected.
- Have students select a criterion (needles/no needles, grassy/shrubby, etc.) and group their plants into two basic categories reflecting one major difference between them.
- Continue this process of categorizing and subdividing. Remind students that with each separation, a new criterion must be recorded.
- Ask groups to report back to the whole class the criteria they established for classifying their plants, and list them on board, chart, overhead projector. Discuss similarities and differences among criteria selected by the groups. Point out that how the separations were made depended upon the starting-point the team selected.
- Distribute Plant Identification Guide showing leaf forms, shapes and margins to demonstrate how botanists identify plants. Ask students to circle the categories they used to identify plants they examined.
- Discuss development of dichotomous keys, a process of dividing and subdividing specimens into groups based on their differences. Distribute Plants of MSH Lahar-Key as an example.
- Assign teams the task of developing their own dichotomous keys for the plants they have collected. Encourage them to include scientific names and terminology wherever possible, and to supplement their key with illustrations. Provide class time for sharing the teams' products.
- Conclude with discussion of reasons for using, and other possible applications for, dichotomous keys.
- (Part II) Assign students to three groups, and each group to observe one of the three plots (three separate ecosystems.) Their objective is to identify, classify, and record plants, number of plants, and animals or animal signs found; and describe soils in their own terminology. Ask students to be thinking about what this information might tell them about the history and future of the plot. Distribute multiple copies and explain handout, School Site Observation Record.
- Give each group about 20 minutes at each ecosystem plot, rotating groups until each has examined all three areas. Provide time for groups to share their observations, as these may stimulate additional observations by other students.
- Divide each of the three groups into three smaller groups or pairs. Have these teams share observations and answer questions 1. and 2. at the bottom of handout, School Site Observation Record.
- Conduct a whole-class discussion of students' observations: similarities and differences among the ecosystem plots, probable future changes, etc. Review the definition of ecosystem, including associated food chains.
- Have students demonstrate their learning by completing the Ecosystem Essay/Self-Evaluation handout.
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