Two Slides Enter an Alleyway – Only One Returns!

One of the commenters asked for examples of what I thought were examples of (relatively) poor material design and (relatively) better design. I’m not trying to weasel out here by using (relatively). These things are relative. Both slides I’m going to show you have good and bad points. From my experience, one is less well-received than the other and I can list some reasons for it.

Both slides are from first year courses, one taught in 2006 and one taught in 2011. The first is Powerpoint, the second is Keynote. (All copyright and page number data has been removed.)

Here’s number 1, which is a ‘not so great’ example.

An example of a cramped slide which is confusing.

And here’s number 2, which is probably better:

An example of a better slide.

So, what are the major differences? To me:

  1. Slide 1 is cramped and hard to read. Following the long yellow lines, despite the fiendishly good contrast, is difficult.
  2. Slide 2 is simple and pretty easy to read. To be honest, it’s also covering much less ground but its intention is clear. The little node structure, which graphically links this slide to all previous work on linked lists.
  3. Slide 1 is not a relaxing slide to look at – imagine that dominating a darkened lecture theatre.
  4. Slide 2 has clear separation between English and not-English, very easy on the eye.

Slide 1 is a multi-stage proof, an extended working piece that takes multiple slides. Slide 2 is a revision slide and summarises the core of a previous concept in one slide, allowing the lecturer to add information, question the class and embellish. The class will have read Slide 2 in a short time and then be able to concentrate. People will be starting at Slide 1 for some time, trying to follow the lines and work things out.

So there are, as promised, some examples for you. Do you agree with my assessment? There are many other things to say about both. What do you think?

6 Comments on “Two Slides Enter an Alleyway – Only One Returns!”

  1. billb says:

    Thanks again, Nick!

    I’m in agreement with your take on the difference. I wonder about your experience popping more quickly through slides like #1 as you talk rather than more slowly through slides like #2. Do you pause to let them take it in, or do you keep on talking sure in the fact that they’ll catch up since there’s only a smaller amount to take in?

    Of course, now that I know I can have my pony when I ask for it, I’d love to see the (relatively) good version of the merge sort complexity proof. I presume it evolves into a series of connected slides with pleasing typography and some sort of breadcrumbs or diagrams to tie the sequence together.


    • nickfalkner says:

      Slide 1 is part of a run of slides that slowly clog up the screen with ugly looking pseudo-equations. Ultimately, slide 1 is not there as a cheat or a ‘cop out’, to quote a commenter from the FB feed, it’s to illustrate that it’s possible to do everything wrong. Clogged, no focus, vague and handwavy maths. I would try to step through these slides quickly but, if someone got lost, where they do look on the slide to start again?
      Slide 2 looks simple but that’s half of its pleasure – it is summarising just about everything they learnt over 1-2 lectures IN ONE SLIDE. Remember the picture, students? There it is. There’s the code equivalent. Here’s how it works. This expresses most of the core of linked lists in one go, with the C code required to link it together. The only thing missing is a diagram that shows Node * linking to ANOTHER NODE *. But I thought it made it a little cluttered. Like I said, it’s not the best, but it’s better.
      The ‘good’ merge sort, for me, would be built up from a lecture on merge sort itself, which describes the complexities in abstract terms, followed by an introductory slide on recursive proofs. Then the detail would go to a tutorial exercise, where students would be walked through the proof, discussing it and then we’d release a summary of the proof as a document. If I had to do the whole thing in lectures, then I would lead on from merge sort and sort a small list (8 elements) and build up the processing load of sorting and combination, then merge those ‘numbers’ into an equation and have a single equation on the board.


  2. Peter Evans says:

    Since the content isn’t really comparable, the thing that strike me is how this illustrates the evolution in fashion, possibly even progress, over the last few decades. A few years earlier, Slide 1 would have been black on white, possibly even in *TeX. Today we have soothing mildly-contrasting happy blues and beiges everywhere we turn, so that those green boxes in Slide 2 look almost garish.

    A few years earlier, Slide 1 would have been scribbled on the blackboard, with much erasing of intermediate steps and frustrated scribbling by the students. Or else it would have been a tutorial problem


    • nickfalkner says:

      I’m going to follow up on this post but my argument is that Slide 1 shouldn’t be a slide at all. The concepts in Slide 2 are actually very complex but the idea is communicated immediately. You know what you should be looking at. That mathematical proof, which is part of an n-slide run in the original lecture, has no focus, no guidance, is boring and if anyone gets lost, they’re sunk.

      As I’m going to post, Slide 1 belongs as an exercise in a tute, with a summary provided later for revision. You can introduce the concept of recursive proofs into a lecture but to walk everyone through it over 15 minutes while they’re reading it or – more likely – going to sleep? TORTURE! đŸ™‚


  3. Ian says:

    I think the first slide looks awfully familiar.

    Also, for the second slide the contrast between the beige background and the grey font might not be sufficient for those in your lecture who are colour blind to some degree. Try out using the Contrast Analyser to see how they would fare :


    • nickfalkner says:

      As it should, Ian! On your second, and excellent, point, the real slide is darker in presentation than it is in this rendering. The Uni projectors make some contrast changes when they project and it does make a difference.

      Thanks for the useful link! I usually check in both black and white and colour-blind rages (there’s a previous post on this somewhere, last week I think) but this is a handy resource for a lot of people.


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