By this class, students should have completed their figure, written their methods, and had their methods followed. Usually only about 50 percent are actually there, but they're coming along.
The main purpose of this class, is to practice comparing the two figures, separating observations from inferences, and organizing RESULTS and DISCUSSION sections. For this purpose, I have collected together many examples of figures from previous semesters that they can practice on.
I've looked for a long time for an accessible reading for students to discuss the idea that observation and inference are inextricably linked. I've used an article by Fodor which was OK, but too high level. And several other things that were contextualized, but the context was too distracting. There was a nice section in Rudwick's Great Devonian Controversy that might work, but I worry that the context will still be too distracting. Instead, for the past couple of years, I've asked students to do a pre-class activity where they provide an example of an observation and inference. This has worked pretty well to get them thinking in the right direction.
I've learned to provide a little therapy up front to students before we do the practice activity. There's nothing like suddenly discovering all of the factors you never realized to control or document. Some students panic that they need to redo their figure or rewrite their methods. So I remind them that a primary purpose of the activity is to help them learn this stuff and it's OK that they didn't know it beforehand. And that if they did, we wouldn't need to do it in the first place. But it drives home the need to actually try methods out before you use them, a lesson which I hope they carry forward to their Proposals.
For the activity, I have them start to compare the figures. I ask them to remember the Writing from Experience activity: to start out just making a list of things they notice. Many students want to jump forward to conclusions like "It's a different tree" and I ask them to back up and indicate what they can see that allows them to draw that conclusion. I wander through the room answering questions and looking at what students are recording. Then I ask them to begin to separate observations from inferences and to identify factors or variables that were different.
I provide some scaffolding along the way. First, after making a list of observations, I encourage them to try to separate their list into observations and inferences. And to try to organize the observations into an outline that presents them systematically: I ask them to recall the narrative-to-exposition activity where we came up with categories and organized their activities using a framework other than time. Many students default to organizing around what they noticed first. Or what was the "most noticeable" difference, so I caution against these.
I also caution against making judgments: the goal is not to assign blame or say that differences are caused by errors — or to speculate about what might have happened or would happen under different future circumstances. But rather to simply observe differences and identify factors dispassionately. This is really hard.
Eventually, I ask them to present the two figures they compared side-by-side and give a quick presentation of first, just differences, and then the factors that they identified. And then I invite the other students to find other differences they might have missed. If the class is small enough, I encourage everyone to present, but frequently the class is large enough that there really isn't time. I try to gently point out when they're describing inferences rather than observations. Or making judgments.
As we go through, I often take a few minutes to show them how to use ImageJ to collect data about differences: to measure items and to compare colors. And to emphasize that there is an immense amount of data available in the figures.
Before the end of class, I remind them that their rough drafts are due next week and that they should come to class ready to present their findings and to take notes of any feedback from the class that they can use to improve their analysis. I point out that I will start commenting on their rough drafts as soon as the next class ends and that I can give much better and more useful feedback if their manuscript is complete and as good as they can make it.