Re: [Phys-L] Edu Videos

[John Denker <jsd@av8n.com>]

On 03/28/2013 06:51 AM, Paul Lulai wrote:

> I don't think one's objections to a single video mean the series
> isn't valuable.  I know you didn't state many comment on the series,
> but a strong opposition to one video can seem like an oppostion to
> the series. The creator of the video has done some research on how
> effective videos are in getting people to learn content.  He found
> explicit statements had very little effect.  He found that when he
> asked people content, elicited responses, and then addressed them,
> there were positive changes in student understanding. I find this to
> be a video version of the Physics By Inquiry approach that also has
> some research and data behind it.

We need to talk about that.

Now and then, somebody advertises a great new pedagogical method for 
teaching "understanding" and "critical thinking".  All-too-often, I 
find that he gets the physics wrong.

That proves to me he is wrong twice over:  Wrong as to content, and 
also wrong as to pedagogy ... because if the pedagogical methods were 
any good, his students would have *understood* things well enough to 
realize that his version of the content was wrong.

I have now looked at several of the 100 or so veritasium videos:
 -- the relativity episode
 -- the most popular episode, the one about venomous creatures
 -- the second-most popular topic, multiple episodes about dropping a slinky

The relativity episode has been discussed.

The venom episode is another example of flogging a misconception in order
to attract attention.  AFAICT Derek Muller was the only person to have
this particular misconception ... until he went to a lot of trouble to 
spread it around.  The most interesting parts of the video consist of a 
hodgepodge of information unrelated to the nominal topic, such as first 
aid procedures for snake bites ... but even that is misleading, possibly 
dangerously misleading, because at best it applies only for a very particular
type of snake-bite.  It is quite inconsistent with the Mayo Clinic instructions
for first aid for snake bites.

The slinky video is more complicated.  The video presents some data that
some people will find surprising and hard to explain.  As such the video
is valuable, especially if you turn off the sound.  The video goes on
to tell a story that comes "close", but doesn't actually arrive at the 
right answer explanation.

Anybody who knows anything about fluid dynamics would take one look at
that video and say "that's a shock front".  

The point is, the "falling part" of the slinky is falling very much /faster/
than the speed of sound for longitudinal waves on the slinky.  The expert
on the video mumbles a few words about the speed of sound, but never squarely
faces the fact that his theory doesn't explain the observations.

Now that you know the magic word, you can find the right answer by googling:
  http://www.google.com/search?q=slinky+drop+shock
As you might imagine, Bill Unruh got it right:
  http://arxiv.org/pdf/1110.4368.pdf

And yes, I did figure it out for myself.  Otherwise I wouldn't have known
what to google for.

Bill rightly brought up the idea of a spring that can pass through itself.
Actually IMHO he downplayed this a little bit, because such a thing does
exist, namely a /conical/ spring.  It's not a slinky, but it does exist:
  http://www.google.com/search?q=conical+spring

There are lots of nifty applications for such things.

==============================

The more I think about it, the more skeptical I am of the suggestion 
that the Jaywalking interviews are OK, because somehow they connect to
the idea that it is good for students to formulate hypotheses before
doing the experiment.

That argument only applies if you think the main audience -- the youtube 
viewers -- were supposed to identify with the hypothesizers, i.e. the 
Jaywalking interviewees.  And in that case, the argument is worse than 
nothing, because on the video, every hypothesizer is an object of ridicule.

Let's be clear:  We agree that there are ways in which it is valuable
to have students formulate hypotheses.  However, jeepers, this is not 
one of the ways!

========================

Teaching requires getting the content right *and* getting the motivation
right.  Neither is a substitute for the other.  Going waaay far in the 
direction of razzle-dazzle is not an excuse for getting the content wrong.

=============

Veritasium bills itself as "an element of truth", abbreviated Ve.  Yes, 
the videos do contain an element of truth.  However, the Ve is greatly 
diluted by Bs.