NOTES TO FACULTY

For "take home/group" students first work on the figure and accompanying explanation of the experiment on their own as a homework assignment. In class they work in small groups (or pairs), explain the figure to each other, and then discuss it together. After this you project the data and go into a class discussion.

This figure could also be used in a think-pair-share exercise in class. I suggest the take home component because there is a good deal of information both in the figure and implied by the findings, and a thoughtful analysis will require a fair amount of time for students. Also most inexperienced ecology students are especially challenged by ecosystem approaches such as input/output comparisons; they have little or no familiarity with these ideas.

Discussion Questions:

• Why did the researchers use herbicides to inhibit plant growth for 2 years following deforestation?


• Streamflow increased in streams exiting the deforested watershed. Why? Where did the water come from?


• The Hubbard Brook researchers selected a site with impermeable bedrock. Why was this critical to their experiments?


• This is an ecosystem-scale watershed study. If you were to design an input/output ecosystem study such as this what would you need to think about in selecting a location and habitat type (e.g. grassland, lake).


• Ecologists who do manipulative field experiments should consider the ethical aspects of their actions. Some manipulations are quite minor (e.g. removing some leaves from a tree) while others are major (applying herbicide to an entire watershed). If you were considering using an herbicide in a field investigation (and even the very environmentally conscious Audubon Sanctuary researchers do this on occasion), what would you want to know about the herbicide and its effects?


• What are some of the implications of the Hubbard Brook research for conservation and pollution research and policy?

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Student Assessment: 1) Diagram with essay quiz.

      Ask students to write a brief essay (define approximate length) to address the following question. One striking result of the Hubbard Brook Experiment on watershed 2 was the large increase in nitrate in streamwater exiting the watershed. Use a simple drawing to show the source of this nitrogen (e.g. where did it mainly come from?) and how this nitrogen is converted into nitrate which ends up in the streamwater. Be sure to use these terms; organic nitrogen, ammonium, nitrate, leaching, bacteria. Write a brief explanation of your drawing.


Student Assessment: 2) Pressing question.

      Students write 3 "pressing questions" about the experiment or figure on a 3x5 card which they hand in as they walk into class (this is also an easy way to take attendance). You select some of the cards, read a few questions, and ask students to discuss or answer them.



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.