Some comments on the Khan Academy videos

Making a teaching video is much harder than it appears. My Q*Bert video was built out of 30 second chunks and many, many retakes. Even then I had to do some sound editing of ‘well’ and ‘um’ and so forth. I don’t have this problem teaching to students in person (even if I’m doing most of the talking) because I can always pause; “dead air” isn’t nearly as deadly. Salman Khan’s use of continuous takes at 8+ minutes is quite a feat.

Video is not just spoken text. Salman doesn’t fully utilize the video format, but he wouldn’t be able to be so prolific otherwise. Even so, what he does is non-trivially different from text. Consider Why Gravity Gets So Strong.

Here’s a shot of the video early on…

… and here’s a shot later.

In a book format one could have a diagram that is progressively developed (but often is not for space concerns), but even given that in the video there is focus and movement going on that gives a more tactile sense of mass that a static image cannot convey.

Video cannot utilize student response the same way as other forms of interaction. I had several points in my Q*Bert video with requests to pause, because it was intended for front-of-classroom use by a teacher. However, some students have seen (and used) it solo. While I did receive one email inquiring about the puzzle at the end, the number of students working alone that paused the video in the middle when prompted I estimate roughly between zero and zero.

Hence, saying “let’s think about this” and giving several minutes wait time is not plausible. (I do have some ideas for how I might get students more willing to pause and may incorporate them in my upcoming video, but I don’t have high odds that they will work.)

Salman Khan cares getting students to understand why things work more than he is alleged. His Slope and Y-intercept intuition video, for instance, shows off an interactive applet that students can use to explore. Even taking a non-interactive portion of the site, like Proof: log a + log b = log(ab) nets a quote like:

What I actually want to do is stumble upon the logarithm properties by playing around. And then, later on, I’ll summarize it and then clean it all up.

Of course, optimally, we’d like the students to discover things and clean them up for themselves. That is asking for something different than a video (or at least how we normally think of video, presented linearly). Even then, for the students who worked through an exploration on their own but still didn’t get it, it’s nice to have a video leading through the same logic as a backup.

Now, it’s not to say there aren’t issues, but some of the bobbles and mistakes — at one point fixed by a pop-up box on Youtube, but I believe that video has been remade now — come through more as humanity and charm rather than obscuring factors.

I can hardly claim speed-recording as many lectures as Salman Khan has allows him to fully utilize the video format. There’s all sorts of dynamic aspects of design that would help with presentation, but they are of course time-intensive. It’s like complaining about Wikipedia and recommending Scholarpedia instead for all work. Scholarpedia only has a fraction of Wikipedia’s content and in all likelihood a particular topic X will not be found in Scholarpedia. It’s only usable as a resource in reverse: looking at the index and reading from there.

Still, in many topics, Khan’s not the only game in town. A common sorted index akin to how The Online Books Page sorts books would be welcome. Khan has a consistent quality that makes him usable; random Youtube choices often lead to some extraordinarily dull math videos. Competition between videos needs to open up in a coherent way that students can navigate; this will push in some better lessons in the gaps Khan has.

Example: By all rights, Dr. Taton’s videos should have more views than they do, try say–

The Complex Number i is NOT the square root of negative one!

However, I’m not going to blame Salman for getting famous and being dubbed The Messiah of Math and so forth. Critiques should be measured and backed by solutions: there’s a chance here to build something new.

11 Responses

  1. If you really want a pause, split the video into separate ones, and end one with “When you’ve thought about this for five minutes, go look up the next video.”

    Don’t make the pause be optional—make the continuation optional.

    • Lots of people (including sometimes admittedly me) are not willing to click on ‘part 2 of 5’ even on shorter videos.

      It still seems like a plausible experiment, though.

  2. Jason,
    While you make some great points here, and I’m willing to totally concede that making these videos is hard, and putting together 2000 of them is a superhuman feat, I still find much more about KA that causes me to worry about than I find promising.


    Kahn makes no attempt to utilize the wisdom teachers, pedagogy or education research. I watched the video you highlighted, and while it was better than some of his other videos on physics (which I would rate as actively harmful to physics learning), it still is quite confusing—it doesn’t get across the truly big idea that the gravitational force exerted by the black hole and the equal massed star is the same when you are far from the surface of the BH, which helps to address the misconception students have that BH’s “suck up” everything around them. He really doesn’t explain correctly why light can’t escape from a black hole, which would require discussion of escape velocity and energy, he just makes a hand-wavy argument that the force is greater at the surface if you compress the mass into a smaller radius. Of course, this idea doesn’t really hold up for a real black hole—a signularity, with no radius. All of Kahn’s work in this video is just trying to play with plugging in numbers to the universal law of gravitation. Again, this is fine, but I don’t think he’s really giving his viewers a deeper understanding of black holes.

    Kahn could do way better by engaging teachers. When I teach this, we work with a lot of simulations, and we do active demos where we stretch out a big sheet, and place objects on it to notice how those objects deform the surface of the sheet, and the path that marbles (which serve as small masses) take around larger objects. There are many better ways to introduce the topic Kahn is dealing with here, but he won’t find any of them because he doesn’t engage any teachers (notice that all KA videos are of him alone—why not open KA up to allowing other teachers to post content? He’s been promising to do this for a while….Why not hire some teachers to consult? All he’s been hiring is programmers….

    Kahn’s history videos are even worse—he flat out admits to wikipedia-ing them, and they don’t really do anything to show students what historians do, no consideration of primary sources, conflicting accounts, etc

    Kahn could use education research. There’s lots of research out there that shows students learn more when presented with a dialogue, when confronted with misconceptions, and when actively involved with learning. Kahn could easily modify his videos to do this, but he doesn’t.

    Finally, while I won’t begrudge Kahn his fame, I think it does come with some responsibility not to simply be a pawn in Bill Gates’s agenda, and to undertake an active effort to participate in the dialogue about education, rather than simply offer up his own solutions. I’ve watched a bunch of his interviews, and he seems to have a rather low regard for teachers, particularly when it comes to how well they might know their subjects.

    • Kahn could use education research. There’s lots of research out there that shows students learn more when presented with a dialogue, when confronted with misconceptions, and when actively involved with learning. Kahn could easily modify his videos to do this, but he doesn’t.

      Not really disagreeing with any of your points, especially regarding history, but the last part (being actively involved) is the key one, but again, very hard to do with the video format.

  3. While I love the Khan videos, the real benefit of Khan Academy is not the videos themselves. The huge thing is the software. I truly believe (as has been stated by others) this is the future of education.

    Using the software, students can learn at their own pace and receive great feedback on their achievement level. But the real advantage is that the teacher only needs to get involved to intervene.

    This is more than just a homework tool folks. This is something that has the possibility to be a game changer, and not just for K-12.

  4. There’s a lot of discussion about whether Khan’s videos are Good Or NOt. I work with adult learners who struggle with math … and I’ve gotten to understand just how badly confusing we make things if we’re not careful. ( has my comments about one of the Khan lessons.)

    … I think, though, that lots of people need a teacher to make sure the ol’ cognitive light bulb is going on, at least here and there.

    We have another program — over ten years old, but good videos with simple interaction. (Modumath) It has been much more of a “game changer” for my guys than things like Khan because it’s simply more carefully made. I mean, when I hear the subvocalization, and it includes “Wow!” … I’m pretty sure the right things are happening.

    • That’s a good example. You would think average would be easy to teach!

      • The videos remind me of my early teaching — I’d put something together and simply be confident that it was a cogent, clear explanation. Then I’d watch what happened… but because I could see my students, I could tell when things weren’t working. Khan is likely to hear far more from fans — after all, who’s going to say “I know, everybody else loves this stuff, but … guess I’m too stupid!” ?

  5. Is the Modumath a paid thing?

    • Yes, and now it’s online subscription only … and while the software version had tests for each lesson (10-12 questions with immediate feedback), with the online version you have to find the pdfs of the tests and print them out. The videos are very good — explanations with drawings & pictures — and students here a minute or two, and then get asked a question, and then gets feedback to their answer.
      I really wish they’d pursue re-doing it with more modern technology so I don’t have to 😉

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: