NOTES TO FACULTY

Pairs-share

For this pairs-share approach give half the class the Sousa data and the other half the Lubchenco data (that is, individual student are given - or have access to - one of the data sets). Students first work on the data sets alone. This can be done in class or as a homework assignment. In the next step the "Sousas" talk to each other ("Lubchenchos" as well) to make sure everyone understands their data well enough to explain it to someone else. Then allow students to pair up in class: the "Sousas" explain their study to the "Lubchencos" and visa versa. (The directions to students asks them to write down similarities and differences between the two studies which emphasizes the application skill. If students do this be sure do ask for examples from their lists.) Finally, show each data set to the class as a whole and lead a discussion and ask questions.

You can also simply project the data and lead a discussion, or alternatively ask students to think-pair-share and then go into discussion.

Either study will nicely introduce the concept of disturbance to students because the approaches are straightforward and the data quite accessible. In addition, the research does not focus on catastrophes such fires or hurricanes, and therefore students can better appreciate how ecologists define and study disturbance (e.g. that it is not "bad"). Both studies look at disturbance on a small or local scale and could also stimulate a discussion of the importance of scale in ecological thinking.

You might choose to tell students about Connell's ideas concerning the intermediate disturbance hypothesis and ask them to explain how the studies test the hypothesis.

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Sousa study

You can use both the figure and table or just one of them. For a quick introduction to disturbance, project only the figure (or table) and lead a discussion.

Discussion questions & topics include:

• Contrast the likely life history characteristics of the most abundance species on boulders that roll over often vs. those that move seldom.


• Describe what typical boulders in the 3 disturbance categories would look like (e.g. the kinds of organisms, other characteristics).


• Sousa measured movement of the rocks with a spring scale. What assumptions did he make using this approach?


• For many years ecologists have debated what is meant by "disturbance". What aspects of disturbance does Sousa look at in his study? (Here you might ask students to list different possible ecological meanings for the term disturbance. These might include catastrophic events such as hurricanes, small-scale events such as tree falls, man-made vs. more natural events, and disturbances caused by organisms including herbivory or diseases)

For practice on data manipulation and presentation ask students to make a figure from the data in the table. They don't necessarily need graph paper for this; they can simply sketch the figure on a piece of paper. You could ask students to sketch the figure on their own first and then compare their figure with efforts of others around them before going into a general discussion. Time allotment for this exercise will depend on the students' familiarity with making figures and with means and standard errors. This exercise emphasizes application and analysis.

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Lubchenco study

For a simple discussion you can use both parts of the figure or just the tidepool data (which is most commonly seen in ecology texts). Students may not be familiar with double Y plots and you might want to explain this ahead of time. Most students will also not know the Shannon-Weaver index. To introduce the index ask students how they would measure diversity of species in a place (use a local example); students will likely say that they would count species. Follow this by asking the limitations of a simple species count and lead into a discussion of uneveness of species distributions.

Discussion questions include:

• What are some different ways that ecologists could examine food preferences by snails in the laboratory (experimental designs)?


• Describe the appearance of tidepools with few, some, many snails - if you were standing next to the pools, what would they likely look like?


• Explain the interplay between physical disturbance and competition between algae in the lower intertidal exposed rock zone.


• Why might snails prefer some algae over others?


• Imagine what 300 snails m-2 in a tidepool looks like. Is this a reasonable density for snails in this habitat? Why is this an important question?

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Student Assessment: Take home or in class essay quiz.

      Use one or more of the questions above as a test question and ask students to write a brief essay.


EVALUATING AN ISSUE: How do you know whether it is working?

      On-going (also called formative) evaluation of the approaches your are using is critical to the success of student-active teaching. Why try out new ideas if you don't know whether or not they are working? This is a brief overview of formative evaluation. For more information, go to the Formative Evaluation essay in the Teaching Section.

Course Goals:

      Formative evaluation only works if you have clearly described your course goals - because the purpose of the evaluation is to assess whether a particular technique is helping students reach these goals. For instance, most of us have "learn important ecological concepts and information" as a course goal. If I reviewed the nitrogen cycle in a class, for evaluation I might ask students to sketch out a nitrogen cycle for a particular habitat or system. Each student could work alone in class. Alternatively, I might ask students to work in groups of 3 and give each group a different situation (e.g. a pond receiving nitrate from septic systems, an organic agricultural field, an agricultural field receiving synthetic fertilizer). The students could draw their flows on a large sheet of paper (or an overhead transparency) and present this to the rest of the class.

The Minute Paper:

      Minute papers are very useful evaluative tools. If done well they give you good feedback quickly. Minute papers are done at the end of a class. The students are asked to respond anonymously to a short question that you ask. They take a minute or so to write their response in a 3x5 card or a piece of paper. You collect these and learn from common themes. In the next class it is important that you refer to one or two of these points so that students recognize that their input matters to you. The UW - FLAG site (www.wcer.wisc.edu/nise/cl1/flag/) gives a good deal of information about using minute papers including their limitations, how to phrase your question, step-by-step instructions, modifications, and the theory and research behind their use.