Tuesday, September 27, 2005

Teaching scientific reasoning.

Actually, make that "Trying to teach scientific reasoning to a group of students, the majority of whom are kind of freaked out about science."

Julie said I should blog about my online Philosophy of Science class. (She was a student on its maiden voyage; if she wants it blogged, it must be blogged!) So, given my thematic focus on this particular blog, I thought I'd discuss one particular type of activity I use in that class that aims to give students a feel for how scientists reason.

Of course, there are loads of activities that could fit under the broad umbrella of "scientific reasoning". There are computations (the kinds of things science majors do on problem sets). There is the activity of interpreting outcomes of experiments in the lab (and, unless things have changed a lot since I was an undergraduate, the task of working out a plausible explanation in the lab report of why things didn't work as planned). There is the challenge of framing a question and designing a research study or experiment that will lead to an answer. I could go on ... But, in my Philosophy of Science courses, as in most others, we don't have labs, and if I asked my students to do computation-heavy problem sets, they'd come after me.

So I go with what philosophy offers here: the thought experiment. For Philosophy of Science, though, these are thought experiments that are conducted in small groups. This is not just a strategy for making the online class feel more like a class (with other people! and discussion!); I give an analogous set of activities to the "live" version of this class.

The thought experiments I give are frequently drawn from incidents in the history of science, or from classic science fiction examples in the scientific literature. The groups of students are presented with a scenario and given a task along the lines of figuring out how to classify particular substances (by macroscopic properties? by microscopic properties?), or how to choose between two competing theories, or how to design tests for kooky-sounding hypotheses. In most of these tasks, the students start with some sort of interpretive framework cobbled together from the course readings, any prior scientific training they might have, and common sense. They need to use this to respond to certain bits of evidence or information. Before they can draw the conclusions they need to answer the questions I'm asking them to answer, they usually need to get more evidence, or adjust their interpretive framework, or both.

As a bonus, because this is a group exercise, the members of the group frequently have different interpretive frameworks and background assumptions. This means that part of the discussion is the gladiatorial battle between different interpretive frameworks and background assumptions. At the very least, the students become aware of their own assumptions and interpretive frameworks through this clash. (Usually they're so light you can hardly tell you're wearing them!) Often, the groups will succeed in coming to something like consensus by the end. Believe it or not, the consensus is usually built by the exchange of reasoned arguments.

This is lesson #1: Scientific exchanges often involve significant disagreements, but scientists work to come to agreement through rational engagement with each other. (This is why the groups are essential; most of my students don't disagree with themselves enough to learn this lesson from a solo project.)

In terms of dealing with the particular tasks I ask the students to complete, they run into some interesting problems. One is that they are fairly slavish in their loyalty to the facts they learned in high school science. Remember, these are students who, as a group, are scared of science. (There are a few notable exceptions -- but these exceptions tend not to be the ones who hold the high school textbook as the last word on the physical world.) Happy as I am that these students have retained something from their science education, it makes it harder to get them into the thought experiments sometimes, since the scenarios frequently ask how you would make a decision given certain sorts of experimental outcomes that might not jibe with reality as catalogued by the high school science class. To get some insight into what scientists do to get to knowledge, they have to imagine themselves into situations in which they might not know all the stuff that we know now and/or the phenomena in the scenario are slightly different from those in the universe they actually inhabit.

Indeed, this connects to another difficulty the students have with the scenarios drawn from the history of science: they think that the most important thing for them to do is "decide" the classification or theory choice in the way that Science actually decided the matter. It's almost like they see the actual judgment of science as the answer in the back of the book. So far, no one has actually overtly tried to reverse engineer their group response from the "right" historical answer, but they tend to use this answer as a selection criterion unless I intervene.

The thing I want them to experience here is that scientists don't have a "back of the book" to look to and check their answers. They're doing the best they can with partial information and an interpretive framework that proves itself in its usefulness. As such, it is completely possible, at certain junctures, that different groups of scientists could come to different conclusions about a particular problem. In the long run, the different groups can be expected to engage each other with reasoned arguments to come to consensus. But, the consensus doesn't come from having absolute proof that you have The One Right Answer. A lot of scientific decisions, after all, have to do with how to draw our categories, or what we want out of a theory or a model or a measuring device.

I mentioned before that I use activities like these in my live classes (where class meetings are 75 minutes long), but I've found them especially effective online. When the discussion happens on the online discussion board, students seem to work harder to express themselves clearly (because they're writing their contributions). They seem also to respond more seriously to the contributions of others in their groups (again, perhaps because they're written). The students have even been know to respond carefully and critically to their own contributions. And, rather than having to discuss and achieve consensus in 75 minutes, my online students typically have a week or two (depending on the complexity of the task) to really dig into the discussion and try to persuade each other. Not surprisingly, the greater length of time makes for a deeper discussion.

Bonus: Since I am privy to all the groups' discussions, not only can I play devil's advocate, dispense encouragement, and clarify any parameters that need clarifying, but I also know who any free-riders are, and I can award credit (or lack thereof) accordingly.

These are little steps toward building up a better understanding of what scientists are doing for the lay persons I teach. But I think they actually convey something that you don't usually get from canned lab experiments, either. (The handful of science majors who have taken this course strengthen my conviction about this.) A lot of the work ion real science is figuring out what to do next given what you've got. The scientist has a general plan of attack and a bucketful of strategies that seem promising and/or have worked in the past, but a lot of scientific reasoning starts out feeling like a shot in the dark.

Philosophers know a lot about taking shots in the dark!

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At 6:09 AM, Blogger Kyle said...

This is a really great post. I came to this post by way of the ScribblingWoman's teaching carnival. I have some questions, but I'll read more of your blog before I ask something that might be found elsewhere.

Thanks for posting this.

At 12:58 PM, Blogger John said...

Thanks for the enlightening post. I am a high school science teacher trying to help my students with their reasoning skills. Is there any hope of getting a sample of your thought experiments? Please email me at jhhaley@hotmail.com. Thanks again!

At 3:56 PM, Blogger inna said...

i, too, would like to try some of your thought experiments with my bio kids(10th grd) or senior bio elective students. thanks! innabinna@earthlink.net

At 7:26 AM, Blogger Anna said...

It is great that sometimes you listen to your students! Clenbuterol


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