Anyone who has listened to me rant about teaching for any amount of time at all has probably heard my rant about the way lab experiments are done in high schools. Students are typically asked to copy a procedure into their lab notebooks (which they do mindlessly while watching talking on IM or watching TV). They get into the lab without knowing anything about what they’re supposed to be doing, and they do their best to follow every detail the step-by-step procedure accurately, so much so that they don’t have the time or brain cycles to step back and look at the bigger picture of what they’re trying to accomplish or how it relates to what they’re learning in class. The next day, the teacher asks “Who can tell me what we did in lab yesterday?” One hand tentatively goes up, and when the teacher calls on the student, the student says, “Um, took this chemical and we, um, mixed it with this other chemical, you know, and it, like, turned blue or something?”
The big problem is that getting through the procedure correctly has become more important than the concepts being taught. If a teacher has only one class period allocated for an experiment, the teacher feels a lot of pressure for the kids to “get it right.” I maintain that you can’t learn effectively unless you have the freedom to make mistakes. My students aren’t given procedures to work from. I teach them the chemistry (theory) and the techniques, and have them design and perform the experiments. (Here’s a link to my experimental design manifesto and lab notebook style guide.)
They don’t always get everything right, but they generally understand what they’re doing, why they’re doing it, and how it relates to what we’re studying in class.
So I’ve started the process of indoctrinating this year’s students. My AP class just did an experiment in which they were trying to measure paramagnetism in transition metals. I gave them a handout that had another teacher’s procedure for the experiment, and told them that they were to do a similar experiment. They were free to use the same procedure or a modified one, whichever they felt would be easier. However, they were to write only a “scheme” (outline/flow chart) into their lab notebooks before doing the experiment. (My students don’t write out the procedure until they’re actually doing it, in case they change anything.)
They performed what appeared to be a successful experiment, but when they came into class the next day only one pair had reasonable results. The other groups had placed the magnet too far from the chemical, and while the balance responded to the presence of the magnet, the chemicals didn’t.
The next day, I handed out a printout of a relevant story from chemistrycoach.com and asked the group that had good data to talk about their experiment. One of them said the key phrase: “We checked our results after a couple of data points and found that we weren’t getting any measurable difference, so we moved the magnet closer.” And that was the lesson of the day–the importance of doing quick & dirty calculations during the experiment to make sure it’s working.
The other benefit of a failed experiment was that the kids now have something that didn’t work in their lab notebooks. They’re still laboring under the delusion that the lab notebook should be a final copy of the experiment, so they write things down on separate sheets of paper before copying them into the lab notebook. *slaps forehead* When I prep them for the repeat experiment on the Monday after vacation, I’m going to start enforcing the rule we had in industry: If you took your data on a paper towel, tape the paper towel with the original data into the lab notebook and sign your name across the piece of tape in such a way that the signature extends onto both the paper towel and the notebook page.
