• During the lesson, confer with students to examine the relationships that exist between living and nonliving factors in an environment. You can gauge understanding by asking questions of the entire class or asking students individually. Listen for misconceptions during group discussion.
• Listen to the use of newly introduced scientific terms.
• Observe students working in groups, taking on various roles.
• Create a list of vocabulary and ideas with which to open discussion the next day.

• “What animals did you hear?”
• “What do you think the sounds mean?”

Wolf: http://simplythebest.net/sounds/WAV/sound_effects_WAV/sound_effect_WAV_files/wolf_howl.wav

Moose:

http://www.rnltruckrepairs.com/ihuntbc/sounds/moose3.wav

After a discussion on the sounds, read this short introduction on Isle Royale to the class:

“Scientists have studied the wolves and moose of Isle Royale for 50 years in an attempt to answer fundamental questions in ecology such as ‘How do animal populations fluctuate the way they do?’ ‘How do predators affect their prey?’ and ‘How does climate affect population fluctuations?’ In the search for an answer to these questions, scientists have created the longest ongoing predator-prey study in the world. The Isle Royale project has made this work available for students to study ecology, population cycles, and species interactions.”

Show students a graph comparing the wolf and moose population changes in Isle Royale National Park (S-B-1-3_Moose and Wolf Graph.doc). Hold a group discussion based on observations of the graph.

• “What trends do you notice about the graph?”
• “How might both populations affect one another?”
• ·         “Does the remote location of the island play a role in this relationship?” 

Step 1: Divide students into collaborative learning groups of four to five students that will work together on the case. Fifteen minutes will be allocated to a review of the relevant ecological concepts and an introduction to the case.

Give groups of students the Ecological Key Terms sheet (S-B-1-3_Ecological Key Terms.doc) and have them discuss and review the words. Have students write any questions they still have on the back of the key word list or on another piece of paper and hand them in. Address questions and/or review key ecological terms and concepts with the whole class before beginning the case study.

Step 2: Give students about 75 minutes total to work through the case study in their groups. The three handouts will be distributed sequentially, not simultaneously. After receiving each handout, the class will be given 15 minutes to read through the material, write out answers to the accompanying questions, and discuss their answers within their learning group. At that point, one of the groups will be chosen to explain their responses to the rest of the class. Ten minutes will be allocated for each presentation and for a general discussion of any points of contention or confusion.

Handout 1: Introduction to the Case Study of Isle Royale

Students in their collaborative groups are given Handout 1 (S-B-1-3_Handout 1.doc) and directed to read it and discuss/answer the questions at the end within a 15-minute time frame. Circulate and listen to student group discussions and guide the discussions by asking questions to deepen thinking, explaining the material on Handout 1, or redirecting discussions that might be going in the wrong direction. After groups have completed the activity of reading and answering questions, choose one group to explain their answers to the whole class. There can be questions and further points of discussion at this time, but the presentation of Handout 1 should fit into a 10-minute time frame.

Optional resources for student groups can include visuals or samples of tree rings to show tree ring growth patterns.

Handout 2: Trophic System Data

Students in their collaborative groups are given Handout 2 (S-B-1-3_Handout 2.doc) and directed to follow the same directions as for Handout 1 (read, answer, and discuss questions) within 15 minutes. Circulate and assist groups with their discussions during the group work time. Be sure to ask questions about student observations of the graph trends and patterns. After Handout 2 is completed, choose a different group to share their answers with the class. There can be questions and further points of discussion, but the 10-minute time frame should be observed.

Optional resources for student groups may include a map of Isle Royale to point out locations where the data on the graph was collected. (i.e., west end, east end, etc.)

Handout 3: Ring Width Indices

Students in their collaborative groups are given Handout 3 (S-B-1-3_Handout 3.doc) and directed to follow the same directions as previously (read, answer, and discuss questions) within 15 minutes. Circulate and assist groups with their discussions during the group work time. Be sure to ask about question 6 in Handout 3, “Design an experiment that would allow you to clarify any ambiguities from Figures 1 or 2.” An entire experiment is not possible during this time frame, but students should communicate their ideas for how to test this question. After Handout 3 is completed, choose a different group to share their answers. There can be questions and further points of discussion, but the 10-minute time frame should be observed.

Step 3: After the last data set on Handout 3 has been discussed, allocate 30 minutes to a final synthesis and an explanation of any follow-up assignments. Thus the total time allocated to this case will be two 60-minute class periods.

To complete the final synthesis, student groups should prepare one of the following follow up exercises.

Follow-up Exercises:

(Choose one exercise or let students choose, depending on the time available or instructional goals.)

1. Write a position paper defending one of four possible conclusions based on the data presented:

• Reject the primary productivity hypothesis and accept the trophic cascade hypothesis.
• Accept the primary productivity hypothesis and reject the trophic cascade hypothesis.
• Reject both hypotheses.
• Reject neither hypothesis.

2. Find and evaluate a second article on trophic interactions from the primary literature. Be sure to include the following parameters:

• What specific hypotheses were evaluated?
• Can you identify the predictions of each hypothesis? Are they mutually exclusive?
• What assumptions are made by the authors?
• Can you identify any caveats to the design or the data presented in the article?
• Do the authors suggest alternative explanations that would also explain their findings? Can you identify alternative hypotheses?

Many of the questions raised in this case could become the basis for problem-based learning exercises. Data relevant to several of the assumptions in this paper have been published elsewhere. Students should be able to find additional information on the relationship between canopy dynamics, environmental conditions, and tree growth rates:

A second case study could be analyzed (example: wolf reintroduction in Yellowstone National Park). See the following Web site for more information: http://www.yellowstoneparknet.com/nature_wildlife/wolf_reintroduction.php

Extension:

• For students requiring further practice with the standards, they can be given a specific energy pyramid, highlighting the organisms that are relevant to the lesson. This pyramid will serve as a resource that students can use throughout the lesson.
• Students could bring together the different elements affecting policy decisions by writing a letter to their state governor either supporting or opposing the reintroduction of predators. They should be required to support their decision with references to the case-study articles or other relevant literature.
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