Manipulating Biology: Costs, Benefits and Controversies

Classroom Activities

Penn Farm Tour and Guest Lecture

Students start the unit by reading in the textbook about Agricultural Land Use and viewing a short video entitled “Feed the World.”⁵² In order to provide context for several of the principles from the video, students tour the school’s fully operational farm where they see such practices as no-till farming, IPM, and various irrigation techniques. As a follow up to the tour, the farm manager delivers a short guest lecture with a question and answer session where students can ask questions based on their reading, the video, and the tour.

Progressive Model Development

In my opinion, the use of development and use of models is one of the most beneficial activities to advance understanding because they engage students in a real scientific exercise that starts with developing a model, evaluating it using evidence, using the model to illustrate, predict, or explain a phenomenon, and revising it to reflect new information. In short, it takes students through the scientific method. In this activity, students work in groups through a process I call “progressive modelling.” An example of this process is demonstrated by Figure 2 below.

Figure 2: Progressive Model Development

Each student starts by creating a basic model. Then, students trade and refine their partner’s model. Next, students trade again and add a 1-2 sentence caption to the model. Finally, the model gets passed back to its original owner who evaluates it for accuracy. Later in the unit, after reading the text and participating in the lecture, students revise their model based on new information. These models now represent students’ understanding of the role GMOs can play in feeding a growing population.

Lecture and Discussion

Direct instruction will be used to emphasize critical content from the reading, as well as deliver new material about the basics of GMO technology. I start with selective and cross breeding before presenting transgenesis and genome editing. At this point students engage in a discussion about the differences in these techniques by using a Think-Pair-Share, where students take a moment to think about their response, share it with a partner and refine their response, and then share out with the entire class. I then return to the problem of a growing population and the potential impacts of climate change presented in previous units and ask students if GMOs can be used as part of the solution to these problems. Students are then given time to research the pros and cons of GMOs (I provide a collated set of resources on Schoology to facilitate this process). After this, students complete a Think-Ink-Share, a variation on the Think-Pair-Share where students must formalize their response in writing before sharing. Students follow up the class lecture and discussion by watching a TedTalk by Pamela Ronald entitled “The Case for Engineering Our Food,” advocating for the use of GMOs.⁵³ This video is posted in Schoology where students are asked to engage in a virtual discussion of the content with their peers. Each student is required to respond to the initial discussion prompt, as well as two responses offered by their peers.

FRQ Practice

Students answer the question number four from the 2009 APES exam on the topic of GMOs, available at: https://secure-media.collegeboard.org/apc/ap09_frq_environmental_science.pdf. Students do not answer part (e) of this question, as it is not directly related to the content covered in this unit. This question is an excellent summative assessment for this unit because it engages students in several of the SEPs presented above and requires them to consider the environmental and economic tradeoffs of using GMOs. It also assesses their knowledge of agricultural practices in general. Part (a) of the question requires students to examine a graph of the use of GMOs over time in developed and developing countries. They are asked to calculate the increase in area of land used to grow GMO crops in both types of countries. Then, using the slope of the line they are asked to predict the amount of land area used for GMO crops in developed countries in the future. Students are also asked to identify one cause for the difference in land area between their projected value and the actual value. In part (b), students are asked to describe one environmental advantage and disadvantage of using GMO crops. In part (c), they are asked to describe an economic advantage and disadvantage of GMO crops. Finally, in part (d), students are asked to describe two agricultural practices that farmers can use to maintain or improve soil quality.

Students are given twenty-two minutes to answer the question to simulate AP exam testing conditions. After answering the question, students trade their answers with a partner and use the rubric released by College Board to score their partner’s answer. The rubric is available at https://secure-media.collegeboard.org/apc/ap09_env_sci_sgs.pdf. Part (a) is worth four points; one point is awarded for each correct answer and set up for that math, while one point is awarded for a correct identification of a cause in the discrepancy between projected and actual GMO crop land area. Part (b) is worth two points; one point is awarded for a description of an environmental advantage and disadvantage of GMOs. Part (c) is worth two points; one point is awarded for a description of a viable economic advantage and disadvantage. Part (d) is worth two points; one point is awarded for each agricultural practice that maintains or improves soil quality. Students total the amount of points earned from all parts of the question. We then use these data to project their AP exam score: s student earning between eight and ten points would be on track for a 5. Students earning between six and seven points would be on track for a 4. Students who earn five points would be on track for a 3. Students earning less than 5 points would not be on track to pass the AP exam.

Once scoring is complete, we discuss the rubric and how to approach similar questions in the future. This discussion typically includes strategies for answering the math-based portion of the question, as well as tips for structuring answers to multi-part questions and strategically using key vocabulary in order to maximize points. Since there are many possible answers to several parts of these questions, engaging with the rubric and each other’s work allows students to further develop their understanding of the topic.