NOTES TO FACULTY

Figures 3A & 3B

Both experiments look at the persistence of escaped transgenes in wild populations. They measure the fitness of hybrids. Figure 3A concerns the relative fitness of weedy radishes and their weed crop hybrids. Six traits were compared to determine fitness. The two types were equal in the performance of four of the traits. However, the hybrids displayed significantly greater fruit and seed production, thus, the hybrids’ fitness was greater than their wild siblings. (You will likely have to explain the term fitness in regard to the measures used here).

Figure 3B is the result of an experiment which tested for the differences in vegetative reproduction characteristics between hybrid and nonhybrid weeds. No significant differences were found between the hybrid and nonhybrid Johnsongrass plants. This lack of difference in observed fitness indicates that the hybrid weeds have an equal chance of establishing and persisting in an agricultural setting.


USDA Hearing

The Student Instructions describe a hearing in which farmers and environmentalists present a case using data from these figures plus knowledge about the topic in general. This will take a full class period and can only be done in a small class. If you do not wish to take this much time for this topic or have a large class, you can use another approach (see Table of Student-active Approaches) to stimulate a discussion.

Students will need time to prepare their 10-minute presentations and anticipate critiques from the other side. One possibility is to create the groups at the end of one class period, allowing 10 minutes or so for them to work on the figures in class. Then assign preparation for the presentations as homework, including gaining background knowledge with the some of the Resources for this issue. In the next class, give students time to polish their presentation before the start of the debate.

Make sure to allow students enough time to discuss both the scientific, social, and political aspects of this topic. After the environmentalists and farmers make their points, allow the USDA employees some extra time to make sure their position addresses the issues discussed within the debate.


Rubrics for presentations & group work assessment:

Students often have more experience writing papers than giving talks. You will need to explain what you are looking for in their presentations. An effective way to help students give more effective oral presentations is by giving them a rubric ahead of time detailing how you will judge the quality of their talks. Spend time in class discussing the rubric as well. For an explanation and an example of such a rubric see: www.siue.edu/~deder/assess/cats/grrubi.html and www.rickhershberger.com/bioactivesite/bio103/symposium/rubric.pdf.

It is often difficult to judge the relative input of each student when they work in groups. In an oral presentation, all students may not speak; how do you know how well each has contributed to the effort? To address this, some faculty have students assess each other. This is clearly a controversial topic for teachers. For an example of a group work assessment form see www.siue.edu/~deder/assess/cats/grp13.html. Students can fill out the form with their names or anonymously. You can choose to give the evaluations back to students or not. No matter how you choose to do group work assessment, explain the purpose of your using this type of assessment and discuss comments and ratings that are useful and ones that are not.

The intention of the Student Assessment question is for students to understand and explain the scientific evidence and information plus additional aspects (economic, political, ethical) of a point of view other than their own. As with Figure Set 1, you will probably need to explain what you are looking for here and give examples of good (and not so good) arguments. As with Figure Set 1, you are asking students to do something with which they probably have little experience: carefully consider the "other" point of view, logically support their argument with evidence, and clearly distinguish between scientific arguments and political/ethical ones. To keep the essay short, ask the students to focus on one or two aspects of their argument. Again, you may have to show by example what you mean by this.

Student Assessment:

Each student should write an essay from the perspective of one of the roles other than the one they presented in class. This essay should demonstrate their knowledge and understanding through concessions and rebuttals to the other sides. It should be approximately one page in length.