TITLE: The Irony of "I Didn't Have Time to Use Your Technique..." AUTHOR: Eugene Wallingford DATE: March 11, 2016 3:59 PM DESC: ----- BODY: All last spring, I planned to blog about my Programming Languages class but never got around to writing more than a couple of passing thoughts. I figured this spring would be different, yet here we are at the end of Week 9 and I've not even mentioned the course. This is how guys like me fail in personal relationships. We think a lot of good thoughts but don't follow through with our time and attention. I am tempted to say that this has been a seesaw semester, but on reflection things have gone pretty well. I have a good group of students, most of whom are engaged in the topic and willing to interact in class. (Lack of interest and engagement was a bit of a problem last spring.) We've had fun in and out of class. The reason it sometimes feels like I'm on a seesaw is that the down moments stand out more in my memory than they deserve to. You'd think that, as long as I've been teaching, I would have figured out how to manage this dynamic more effectively. Maybe it's just a part of being a teacher. We want things to go perfectly for our students, and when they don't we have to wonder why not. One source of concern this semester has been the average exam score for the first two tests. They have been lower than historic averages in the course. Have I changed my expectations? Have I done something differently in the classroom? After taking a hard look back on my previous semesters' notes and assignments, I think not. My job now is to help this class reach the level I think they can reach. What can I do differently going forward? What can they do differently, and how do I help them do it? I know they are capable of growth. Early last month, PhD Comics ran a strip titled The Five Most Typed Words in Academia. The winner was "Sorry for the late reply". At the time, the five most common words my students had said to me in the young semester were:
I didn't read the instructions.
For example, the student would say, "This problem was hard because I didn't know how to take the remainder properly." Me: "I gave that information in the instructions for the assignment." Student: "Oh, I didn't read the instructions." Fortunately, we seem to moved beyond that stage of our relationship, as most students have come to see that the assignment may actually include some clues to help them out. Or maybe they've just stopped telling me that they don't read the instructions. If so, I appreciate them sparing my feelings. A related problem is a perennial issue in this course: We learn a new technique, and some students choose not to use it. Writing code to process language expressions is a big part of the course, so we study some structural recursion patterns for processing a grammar specified in BNF. Yet a few students insist on whacking away at the problem with nothing more than a cond expression and a brave heart. When I ask them why, they sometimes say:
I didn't have time to use the technique we learned in class, so...
... so they spent twice as long trying to find their way to a working solution. Even when they find one, the code is generally unreadable even to them. Functional programming is hard, they say. Fortunately, again, many seem to moved beyond this stage and are now listening to their data structures. The result is beautiful code: short, clear, and expressive. Grading such programs is a pleasure. It recently occurred to me, though, that I have been guilty of the "I didn't have time to use your technique..." error myself. While trying to improve the recursive programming unit of the course over the last few years, I seem to have invented my own version of the Design Recipe from How to Design Programs. In the spirit of Greenspun's Tenth Rule, I have probably reinvented an ad hoc, informally-specified, bug-ridden, pedagogically less sound version of the Design Recipe. As we used to say in Usenet newsgroups, "Pot. Kettle, Black." Before the next offering of the course, I intend to do my homework properly and find a way to integrate HtDP's well-tested technique into my approach. These things stand out in my mind, yet I think that the course is going pretty well. And just when I begin to wonder whether I've been letting the class down, a few students stop in my office and say that this is one of their favorite courses CS courses ever. They are looking forward to the compiler course this fall. I'm not sure students realize the effect such words have on their instructors -- at least on this one. Off to spring break we go. When we get back: lexical addressing and (eventually) a look at stateful programming. Fun and surprise await us all. -----