

Physicists Seek To Lose The Lecture As Teaching Tool - gruseom
http://www.npr.org/2012/01/01/144550920/physicists-seek-to-lose-the-lecture-as-teaching-tool

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kghose
I have always thought of lectures not as a way to convey information but
rather enthusiasm.

A dull (or bad in other ways) lecturer almost always turns me off to a topic.
A lecturer who is excited about the topic _always_ makes me want to know more
about something.

I remember a lecture about insect flight muscles I listened to in 2005. Before
that I never really thought about muscles. For a whole day after that lecture
I wanted to study muscles as my research topic.

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powertower
> He came up with a law of motion to explain how two balls of different
> weights, dropped from the same height, hit the ground simultaneously.

I've been thinking about this for a while.

The two balls hit the ground at the "same time" because relative to the earth,
they are about the same mass (ball #1 is only 1/2 the mass of ball #2, and the
difference between that and the mass of the earth is negligible).

Once you start making ball #1 and ball #2 massively different, one of the
balls begins to attract _the earth itself_ more than the other ball.

For example...

1) Take a basketball, drop it. Measure the time.

2) Take a miniture blackhole, drop it. Measure the time.

While earth's pull will be the same on both the basketball and the blackhole,
the blackhole's pull on earth will be much much grater than the basketball's
and hence the additive acceleration will be larger.

But, if you drop them at the same time, next to each other, things will even
out since the earth will move towards them both as it moves towards the one.

What do I win?

~~~
archgoon
There is no mass for which one ball attracts the earth more than the other
ball if the other (fixed mass) ball is less than the mass of the Earth. The
ratio of the two forces, the force between the varying mass ball (vmb) and the
Earth and the varying mass ball and the fixed mass ball (fmb), is constant°:
m_earth/m_fmb.

°Assuming equal distance between the two objects. It's still constant w.r.t.
mass if you allow different distances, you just pick up a ratio term of the
two distances. Again, you don't 'start' attracting one ball more than the
Earth. You're _always_ attracting the Earth more.

Now that I've put it that way, we can see that the mass doesn't matter, since
the previously neglected force is _only_ operating between the direction of
the two masses, so there is no additional acceleration in the direction of the
earth. If you pretend the earth is a infinite plane (which is typical) than we
can see that this will have no effect on the fall time. Since the distance to
the earth starts being equal, and the accelerations (relative to the earth)
are equal, the time will be equal.

If, however, you instead acknowledge that the earth is a sphere, and we really
started the two objects at rest at the same radius but different angles, than
you have a restricted three body problem and I should probably not try to
solve that before I've had coffee.

Thank you very much. It will be a good day.

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powertower
> There is no mass for which one ball attracts the earth more than the other
> ball if the other (fixed mass) ball is less than the mass of the Earth.

Are you talking about inertia?

If ball #1 or #2 does not have the mass (and hence gravitational pull) to
overcome Earth's inertia ... the Earth does not move towards it.

But wouldn't that force or energy still be conserved and transferred into the
ball's own acceleration?

~~~
archgoon
>If ball #1 or #2 does not have the mass (and hence gravitational pull) to
overcome Earth's inertia ... the Earth does not move towards it.

That is false. I think you are thinking of friction.

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ivan_ah
I had recently come to the same conclusion. All information coming from
external sources only goes into working memory, and does not get transferred
into long-term highly-connected cortical connections. The lecture (or rather
the crash course tutorial) is still pretty good for dishing out lots of
factual knowledge, but then you have to let the students
think/practice/explain things in their own words if you want proper
connections to be made.

I can tell you "In the absence of friction, the total mechanical energy of a
system is conserved", and you can commit this message to memory, but to truly
understand this you have to see this concept in 10-15 different situations.
Only then can the abstract statement be understood. The cool part about
physics is that you actually get a little //knowledge buzz// at that point...

My question to you all, is a book any different from a lecture? On the one
hand, you are still "sitting there" while someone else tries to "pour"
knowledge into you. On the other hand it is pretty good to see things clearly
explained on paper (story telling instinct?) and, just like the Khan videos,
you can "rewind" a few pages back, if you don't understand something. I would
particularly like to hear the younger crown on this one: are books still cool?

BTW, David Hestenes has lots of cool papers out:
[http://www.google.com/search?q=David+Hestenes+test+filetype:...](http://www.google.com/search?q=David+Hestenes+test+filetype:pdf)

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aik
Below is the key concept here. The quicker education administrators and
teachers realize this the better off we'll be.

>>"With modern technology, if all there is is lectures, we don't need faculty
to do it," Redish says. "Get 'em to do it once, put it on the Web, and fire
the faculty."

>>Some faculty are threatened by this, but Mazur says they don't have to be.
Instead, they need to realize that their role has changed.

>>"It used to be just be the 'sage on the stage,' the source of knowledge and
information," he says. "We now know that it's not good enough to have a source
of information."

>>Mazur sees himself now as the "guide on the side" – a kind of coach, working
to help students understand all the knowledge and information that they have
at their fingertips. Mazur says this new role is a more important one.

~~~
gruseom
I'd say this is the key concept:

 _"Students have to be active in developing their knowledge," he says. "They
can't passively assimilate it."_

Lectures don't work because they're passive.

~~~
aik
That's definitely a related key point, and also my main issue with essentially
all of my own education. Although we have the perception of being in control
of our own education (ie. we can choose some courses in high school, can
choose our university and degree), the fact that nearly every time we enter a
classroom, the "passive" hat comes on -- from that moment the teacher is in
absolute control and the student simply has to sit back and follow directions.

Just recently I attended a weekend Launch48 event. In terms of "teaching
styles", the Launch48 teaching style is nearly the complete opposite of the
traditional classroom -- intensely engaging (ie. active) instead of passive.

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Tycho
I don't really understand why lectures have continued since the advent of
affordable video technology. Every year the departments prepare unique lecture
series and deliver them to new students, sometimes the same lecture twice a
week because the numbers are so large, interacting very little with the
audience, and expecting students to really engage with the new ideas they're
exploring this term.

From the student's perspective having a video from some lecturer at Yale or
wherever would be just as effective.

Lectures to small classes of say 10 are a different story, but on the scale of
modern UK university courses it seems like one of the most inefficient systems
imaginable.

~~~
chalst
I think there is an element of motivation here, because students are more
likely to attend a lecture course than they are to watch videos, even if they
would find the video course a more efficient use of their time.

~~~
kmfrk
Either a sense of motivation or one of obligation, since they know that
someone is taking the time to do a lecture.

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Calamitous
You guys don't know many college students, do you?

~~~
kmfrk
"My anecdotal evidence is better than yours."

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csomar
Lectures can be amazing if executed by the right person. The problem, as
stated in the article, is not related to lectures. It's related to the
University and teaching system as whole.

Students come their to get the degree and not to push science forward. Only a
small fraction are actually interested in the science. The rest are just
looking to get good grades.

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mkramlich
I think a lot of what current traditional schools do is merely an echo or
inertial continuance of practices that at best made sense hundreds of years
ago. They developed in a time where the technology landscape was more limited,
there were fewer alternative methods, and the economic competitive context was
less global and more local. Now we have the technology to record the best
video/audio lectures on a given subject once and mass distribute them for
free. We can create software that automatically grades massive amounts of test
and homework submissions. We can push essay submissions into systems that
automatically check for potential plagiarism against large databases of
previously written papers. Instead of dead paper resumes we can have online
portfolios of actual work products and videos showing people directly
exercising particular skills in real time, in order to convey legitimacy and
make purported abilities tangible. With Google we can quickly lookup trivial
facts on the go as needed rather than having to memorize them. All of the
above frees up humans to spend more time learning fundamental ideas and
concentrating on their own health, wealth and happiness and less on mindlessly
carrying out superficial traditions, doing makework or bowing to arbitrary
external authority. We can be more real. And do more, faster and better.

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cottonseed
> Get 'em to do it once, put it on the Web, and fire the faculty.

Even better, find the greatest lecturers out there, get them to do it once and
put it on the web.

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balsam
It's (well) known that learning by teaching beats learning by doing which in
turn beats learning by listening (Something Confucius might have said. Modern
citations welcome.) The fact that lectures still exist must somehow be due to
economic necessities.

~~~
jamieb
Definitely agree, but with the caveat that the teaching occurs after a period
of doing. If I learn something by doing it, and then attempt to teach it, I
may dwell in the "Why" of it when otherwise I might not have. But if someone
listens, and then lectures, that is no better than a video.

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janeklb
A great lecturer can inspire and spark a thirst for knowledge inside
students.. In my opinion there is no way lectures will be completely replaced
or lost. However, learning by doing is probably more efficient in this
information soaked age so I wouldn't be surprised if more integrated labs /
discussions courses started showing up.

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vonskippy
Ironically, blue color trades have known that since their inception.
Electricians, plumbers, carpenters, etc all mix book work with hands on
training. Why shouldn't all academics follow that proven method (after all,
MD's do - can you imagine going to a doctor that only leaned from a book?).

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wisty
Lectures are a great idea, when the professor is an expert talking about
something only they know about. If they are just rehashing Newton's laws 101,
there's no need. It's an outdated tradition dating back to when all university
classes taught stuff that was cutting edge.

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rsanchez1
One thing that my physics professors have consistently said is that students
who do well on homework do well in the course. I think it's because the
students who are motivated to learn the material do the homework to test their
own understanding. My own experience is that time spent in lecture doesn't
really affect these students. In fact, they would only show up for most
lectures if attendance was mandatory. The students who want to learn, learn.
Unfortunately, lectures don't exactly motivate learning. They just seem like
meetings where you discuss what's on the next exam.

if every lecturer had the skill of Feynman, though, there would be no problem.

