Physicists Seek To Lose The Lecture As Teaching Tool(npr.org)
npr.org
Physicists Seek To Lose The Lecture As Teaching Tool
http://www.npr.org/2012/01/01/144550920/physicists-seek-to-lose-the-lecture-as-teaching-tool
14 comments
> 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?
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?
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.
°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.
> 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?
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?
>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.
That is false. I think you are thinking of friction.
The problem becomes even more interesting when you start considering that it matters which frame of reference the timing is done from, if each ball has its own timer contained within then you get to have fun with relativity.
It is important to keep in mind that black holes do not "pull" things towards them, they have the same kind of gravity that any other object has, and are also affected by gravity in the same way as other objects. A "miniature" black hole will land at the same time as the basketball.
And if you drop them at the same time, Ball #1 would probably arc towards the blackhole changing the length of time it took to hit...if it manages to stay outside of the blackhole's event horizon.
If the blackhole pulls harder on the earth than the basketball pulls the earth, the earth also pulls harder on the blackhole than the basketball
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.
>>"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.
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.
"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.
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.
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.
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.
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.
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.
Either a sense of motivation or one of obligation, since they know that someone is taking the time to do a lecture.
You guys don't know many college students, do you?
"My anecdotal evidence is better than yours."
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.
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.
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.
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.
> 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.
Even better, find the greatest lecturers out there, get them to do it once and put it on the web.
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.
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.
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.
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?).
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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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.
if every lecturer had the skill of Feynman, though, there would be no problem.
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.
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:...