Teaching for (current) Humans

da Vinci's Vitrvuian Man. Human figure with arms and legs outstretched showing the ratios of the perfect form.

Leonardo’s experiments in human-octopus engineering never received appropriate recognition.

I was recently at a conference-like event where someone stood up and talked about video lectures. And these lectures were about 40 minutes long.

Over several million viewing sessions, EdX have clearly shown that watchable video length tops out at just over 6 minutes. And that’s the same for certificate-earning students and the people who have enrolled for fun. At 9 minutes, students are watching for fewer than 6 minutes. At the 40 minute mark, it’s 3-4 minutes.

I raised this point to the speaker because I like the idea that, if we do on-line it should be good on-line, and I got a response that was basically “Yes, I know that but I think the students should be watching these anyway.” Um. Six minutes is the limit but, hey, students, sit there for this time anyway.

We have never been able to unobtrusively measure certain student activities as well as we can today. I admit that it’s hard to measure actual attention by looking at video activity time but it’s also hard to measure activity by watching students in a lecture theatre. When we add clickers to measure lecture activity, we change the activity and, unsurprisingly, clicker-based assessment of lecture attentiveness gives us different numbers to observation of note-taking. We can monitor video activity by watching what the student actually does and pausing/stopping a video is a very clear signal of “I’m done”. The fact that students are less likely to watch as far on longer videos is a pretty interesting one because it implies that students will hold on for a while if the end is in sight.

In a lecture, we think students fade after about 15-20 minutes but, because of physical implications, peer pressure, politeness and inertia, we don’t know how many students have silently switched off before that because very few will just get up and leave. That 6 minute figure may be the true measure of how long a human will remain engaged in this kind of task when there is no active component and we are asking them to process or retain complex cognitive content. (Speculation, here, as I’m still reading into one of these areas but you see where I’m going.) We know that cognitive load is a complicated thing and that identifying subgoals of learning makes a difference in cognitive load (Morrison, Margulieux, Guzdial)  but, in so many cases, this isn’t what is happening in those long videos, they’re just someone talking with loose scaffolding. Having designed courses with short videos I can tell you that it forces you, as the designer and teacher, to focus on exactly what you want to say and it really helps in making your points, clearly. Implicit sub-goal labelling, anyone? (I can hear Briana and Mark warming up their keyboards!)

If you want to make your videos 40 minutes long, I can’t stop you. But I can tell you that everything I know tells me that you have set your materials up for another hominid species because you’re not providing something that’s likely to be effective for current humans.


5 Comments on “Teaching for (current) Humans”

  1. Julie Kerry says:

    Thanks – I’m going to start trimming my modules. Or at least break them up into 5 minute sections, with some kind of interactive component in-between!


  2. David Butler says:

    Two thoughts about the 6-minute thing:
    1. I find students have long attention spans when REVIEWING content, as opposed to when they are learning it for the first time. They’ll watch something that goes for two hours when reviewing for exams or when they are already confused (admittedly often pausing it regularly). I’m happy to believe that six minutes is the perfect length for a first introduction, but I think longer is ok for a later stage.
    2. Some things just take longer than 6 minutes. If you want a worked example of a maths problem that shows the entire process, sometimes it does actually take 15 minutes. And at least some students watch the whole thing because they do want to see the whole process. How do you get around that?


    • nickfalkner says:

      My own viewing statistics for review agree with you although I can’t tell you how much they’re watching or how often they pause/switch position in track (yet).

      In terms of longer things, it’s a design issue. An entire knowledge artefact can easily be longer than six minutes but do you actually ask people to hang on without some form of conceptual breakdown? More likely, there are development points (concepts within larger concepts) that you can naturally pause at.

      It’s worth noting that students will most likely be watching you at 1.3-1.7 times speed anyway so they’re already messing with your time.

      At least some students will always watch the whole thing. The problem is that the EdX data tells us what students do overall – and for a predominantly graduate viewership, from known stats. These people should be conceptually more advanced and more able to endure longer videos, although there are selection bias issues because they have chosen to go to EdX of course.

      Why don’t we sit down with that 15 minute explanation and see what it would look like in pieces and if we can find a version that works for you and the 6-7 minute limit?


    • nickfalkner says:

      The other question is “is it actually an interactive activity?” when you do it? How can we capture that in an online sense. It might be video plus action plus more action.


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