Getting It Wrong

Every year during the spring testing season, my high-school students have to take the state-mandated standardized tests needed for graduation.  One year I was serving as a hallway monitor and helping the test administrator to organize and coordinate the various proctors.  He had written detailed instructions for the staff, details somewhat different from the details in the test booklets but details that made sense for our schedule and space constraints.

When it became clear to me that the proctors were confused about the scheduling, and had begun improvising, I reported to the administrator, who then scurried about trying to re-align the proctors, with mixed results.

The administrator and I compared notes later in the day, and he asked if he hadn't made his instructions clear enough.  I replied that they were clear, but because they had differed slightly from the instructions in the test booklet, the proctors had become confused.  "But I said in the instructions to ignore the booklet's recommendations," he said with exasperation.  "I know you did," I agreed.  "Tell me, Bill, how do you explain things to people?" he asked, quite genuinely.

I have no idea where my answer came from.  I don't think I had ever really thought about it overtly, but of course the question cut to the heart of what I do as a teacher.  Without hesitation I replied: "You have to anticipate how people will get things wrong.  Then you can write instructions so mistakes are caught before they happen."

I think about this exchange often, and its implications for teaching.  I can listen to a teacher explaining something to a student and can tell immediately if the teacher has any idea how the student might be getting it wrong.  So much emphasis is placed on getting it right!  But each student gets it wrong in his own way.  An experienced teacher anticipates that, or reads it when it happens.  That's why you can't just lecture students.  They aren't thinking what you think they're thinking.  They're certainly not thinking the way you are thinking.

Experts can have a tough time teaching novices.  The expert was a novice once, but he can't imagine thinking like that now.  Some experts have become so fluid and intuitive at what they do that they can't remotely explain to a novice what they're doing.

I remember watching a video of a piano player trying to show how he played.  When he tried to simplify or even slow his playing down, he couldn't play at all.  So he resorted to vague explanations of what he was doing, and then played as he would have in a performance.  It was entertaining, but not very instructive.

I have taught physics long enough that I know what mistakes to expect from my students, the many ways they will get it wrong.  Sometimes I let them get it wrong, and then guide them to discovering the mistake on their own.  Other times I talk them through the error before they have had a chance to get it wrong.  And at all times, I think a lot about how to explain and describe physics in a way that sidesteps the potholes without oversimplifying the journey.