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Thursday 22 May 2014

Teaching Math with PowerPoint - a post mortem

I taught a second year linear algebra course in the fall term of the 2013 - 2014 school year.  The first few lectures were review of the prerequisite course.  My normal teaching practice consists almost exclusively of writing on the board when I'm not directly interacting with students.  But I figured that since my students had learned the material already, they didn't need to take notes and I could run through it a little faster than if they were seeing it for the first time.

So I put all of the review notes on PDF Slides (not actually PowerPoint, despite what I wrote in the title), using the Beamer package for LaTeX.  The first week went fairly well, so instead of switching back to my usual practice at the end of the review stage, I decided to to continue using slides.  I didn't intend on using them for the rest of the term, but in the end, that's what I did.

Overall, it was well received by the students.  Direct feedback was positive, and I received no complaints on course evaluations.  One complaint that could have been levelled at me is that the slides were not always perfect.  Sometimes there were typos, for example.  Perhaps the students were content with the corrected versions that I later posted on the course website.

Student performance was consistent with other courses I've taught.  A couple of students, but one was a student who was also doing poorly in other classes, and there were extenuating circumstances to explain the other student's failure. 

It would be irresponsible to draw conclusions about the effectiveness of the practice at this stage, mind you.  It was the first and only time I've taught this course and the first time I've used slides to this extent.  Nevertheless, it went well enough that I plan on doing it again in the upcoming year.

Although the course was far more heavily oriented towards slides than any other time I taught, I still did rely heavily on the blackboard.  I believe it's better to work out examples with the students, so I would only write the examples on the slides, and work out the solutions on the blackboard (often putting the final answer on the slides too, though not always).  

I also made heavy use of Beamer's "pause" command.   That way, I could present the text of a given slide gradually, one line at a time or even one word at a time if I wanted to, rather than all at once.  To some extent, this mimics writing on the board, where the content is revealed chalk stroke by chalk stroke.  I think this makes it easier to absorb.  Rather than trying to take in a whole slide's worth of information, only one line needs to be comprehended at time.  I also think it helps to keep the pace of the lecture from getting too fast, an easy temptation to give into with slides (or overheads, in the olden days).

Switching back and forth between the blackboard and the screen was a bit frustrating at times, since it seems that most classrooms equipped with projectors (which is most classrooms, if not all, these days) are not designed to mix the two methods. 

I taught in three different classrooms for the class.  Each room had a different layout with different upsides and downsides.

One of the classrooms had the projector screen covering up one panel of the chalkboard.  This was okay as long as I could fit everything in the other panel.  Occasionally, I needed both, which meant rolling up the screen and turning off the projector, then, when I'm done with the other panel, pulling the screen down and waiting for the projector to turn back on.  None of these are onerous tasks, but they interrupt the flow of the lecture and use up time.

The other two classrooms had their screen covering the middle of the blackboard, with the edges of the boards still exposed to write on.  In one room, the exposed edges were quite large, about the size of the uncovered panel in the other classroom.  In the other, however, they were fairly narrow.  The annoyance in both cases was that if an example took up more than one board, I had to finish it on the other side where it was hard to see what I had written on the first side because the screen was in the way.

Another issue I had is the fact that screen real-estate is quite limited.  Some things could not be fit onto a single slide.  Something on one slide might refer to something on another slide.  On a blackboard, one can use two different panels for the different things, but there is only one screen.

The other problem I ran into was malfunctioning technology.  In one room, the projector bulb burnt out.  In another, I could not access the network to log in to the computer.  Fortunately, computer services was quick to replace the bulb in the former case, and there was another open classroom with a working projector in the latter case.


If I had my way, each room would be equipped with two, or even three, projector screens, one for the current slide, and the other(s) for showing preceding slides or calling up older results or examples.  There would also be a chalkboard with at least two panels to write on, even when all screens are in use.  Of course, this wouldn't be feasible in all but the largest classrooms, and even if it were, it could end up being the classroom version of The Homer.  I'd settle for an effort on the part of classroom designers to consider that someone might want to use both blackboard and projector at the same time.

Despite the space taken up by the above complaints, they were all fairly minor in the grand scheme of the course.  They don't add up to enough to discourage me from doing it again, looking for places to improve, and maybe thinking about trying it for other courses.

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