Score another point for my mother.
My mother is a really good cook. She is also an unrepentant violator of recipes. My earliest cookbook related memory involves noticing that, while Mom had a recipe in front of her, she was flagrantly measuring different amounts of ingredients than those called for, and combining them in a way that clearly contravened the method described on the page.
It turns out that this manifestation of her issues with authority may also explain why she has such a good understanding of what she’s doing in the kitchen.
At least, that’s a conclusion I’m inclined to draw from research done by Ohio State University professor Steve Rissing on two different approaches to an enzyme laboratory experiment in an introductory biology course:
During a talk at the annual meeting of the American Association for the Advancement of Science in San Francisco, Rissing cited one particularly difficult laboratory experiment in which students worked with enzymes. Students often struggled through this exercise, and usually scored poorly when later tested on the implications of the experiment’s findings.
Rissing asked the laboratory instructors – usually graduate students in biology – to use two different approaches over two academic quarters when teaching the experiment. Roughly 300 students, all taking an introductory biology course for science majors, were in each group. The first group used what Rissing calls the “cookbook method” – they followed step-by-step instructions on how to carry out the experiment and display their results. These students were provided with a standard, prepared enzyme solution.
The second group of students had to prepare their own enzyme solutions from a piece of raw turnip. They were also given more freedom to think through their approach to the same experiment, and were encouraged to use critical thinking and hands-on discovery to come up with their approach.
At the end of their respective experiments, both groups of students were asked one simple question: Where do enzymes occur in nature?
About one out of five students (23 percent) in the “cookbook” group answered the question correctly. But 83 percent of the students who developed their own approach gave the right answer, which was that enzymes come from living tissue.
“The students in the first group were just as intelligent as those in the second group,” Rissing said. “They just lacked confidence. No teacher had ever asked them something as simple as how do they want to display what they saw in the experiment. They had always been told how to do that.”
What we’re looking at is the difference between being able to follow instructions and understanding why a particular sequence of steps produces the desired result. Following instructions in a lab protocol precisely is often harder than it seems like it should be, especially if you factor in inexperienced hands (belonging to undergraduates who might not even be science majors) and aging equipment. If you’re a novice in the lab and someone gives you the step-by-step recipe, your attempts to complete the experiment successfully usually come down to trying to complete each step just as described in the recipe. If the experiment doesn’t work, you go back and figure out which step(s) you screwed up. If the experiment does work, what you know is that you must not have screwed up any of the steps too badly.
Unfortunately, that may be all you know: Correctly following this recipe brings about that result. Why this recipe and not another? That might be something the lab instructor knows, but it’s not knowledge that magically penetrates your skull just in virtue of your having performed each step of the experiment correctly.
If, on the other hand, you’re presented with a task and less precise information about how you should accomplish it, it seems like you have to think harder about possible strategies for completing that task. Given the turnip, you need to mull over the range of things you might do to it in order to extract its enzymes, not to mention the possible ways you might determine whether what you’ve gotten from you turnip really contains enzymes (and from there to measure the activity of those enzymes, etc.). Your work is less about performing particular steps in a recipe correctly or incorrectly, and more a matter of sizing up the extent to which particular things you could do bring you closer to, or farther away from, your goal. Messing around in this way gives you a much better feel for what could be happening when you perform a particular operation. You aren’t just following someone else’s map — you’re making your own, and in the process, you’re getting a much better feel for the terrain.
If memory serves me right, one of the constraints that might make the cookbook approach to intro labs appealing is time. You have a finite interval (often 4 or 5 hours tops) in which to get results. Sometimes that gives you room to work through the steps in the prescribed recipe twice, but often you have one shot to make it work.
Coming up with your own protocol means having time for trial and error and gradual refinements. For certain tasks, this approach could easily take multiple lab sessions. These sessions, of course, would be cutting into all the other essential stuff that needs to be crammed into the lab portion of an intro course.
Maybe we should ask if what makes the canonical lab experiments “essential” is that the students have mechanically performed all the steps associated with them, or that the students come out with a good understanding of what is happening when they follow those procedures and of why those procedures work.
In the meantime, on the assumption that it will take time to apply Rissing’s approach to retooling intro lab curricula, I suspect it might be useful if some lab instructors deployed my mother’s attitude toward recipes — helping students to understand how violating different steps of the protocol in systematic ways makes a difference in what happens.