TITLE: The Irony of "I Didn't Have Time to Use Your Technique..."
AUTHOR: Eugene Wallingford
DATE: March 11, 2016  3:59 PM
DESC: 
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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
<EM>they</EM> 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
<A HREF="http://www.phdcomics.com/comics/archive.php?comicid=1854">
   The Five Most Typed Words in Academia</A>.
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:

<BLOCKQUOTE><EM>
 I didn't read the instructions.
</EM></BLOCKQUOTE>

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 <TT>cond</TT> expression and a
brave heart.  When I ask them why, they sometimes say:

<BLOCKQUOTE><EM>
 I didn't have time to use the technique we learned in class,
 so...
</EM></BLOCKQUOTE>

... 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
<A HREF="http://www.ccs.neu.edu/course/cs5010sp15/recipe.html">
   the Design Recipe</A>
from <EM>How to Design Programs</EM>.  In the spirit of
<A HREF="https://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule">
   Greenspun's Tenth Rule</A>,
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 <EM>HtDP</EM>'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.
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