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Lessons I wish I had learned before teaching differential equations [pdf] (1997)

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Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#131

Earlier quoted context omitted.

Should it really though? Maybe pedagogy is just hard and we can't expect constant progress.

Pedagogy, like any other field is constantly developing. We are continually learning new and better ways to teach materials and thus I think the continued evolution of teaching materials has the potential to be a good thing (and I've created curriculum for professional learning, for grad school and for bootcamps). It is true that just because a book in newer it is not necessarily pedagogically better It is also true…

I think that researching pedagogy is very difficult, and, like many scientific fields, it is hard to reproduce results found in papers. (I am not an expert in this area -- I am just a former teacher with around 10 years teaching experience.) One of the main things I notice is that standardized test scores are not really improving. I think that high school students today would score about the same as high school students in the 1980's if they were given the same multiple choice tests. This implies to me that the field has not advanced a lot. I do think that LLMs and other computer based teaching could help.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#132
post #22

“Why is it that no one has undertaken the task of cleaning the Augean stables of elementary differential equations? I will hazard an answer: for the same reason why we see so little change anywhere today, whether in society, in politics, or in science“ I see a lot of parallels with the Physics department and I think the reason is much more depressing. Both fields embrace a sort of masochism and active desire to keep…

What's the problem with a good book, age? Baby Rudin's first edition is 70 and the latest one is from 1976. It's still widely used and will be for a while. Honestly your problem was that you didn't know any Classical Mechanics yet and you were assuming that the volume of recent developments made old books obsolete. Maybe in Biology, in Physics getting to recent developments would mean that you're familiar with Goldst…

I took Lebesgue integration and some pretty high powered group theory classes in the 1989s and am retaking them now, and I have to say the presentation now is much better. I think having Terrence Tao blog about how stuff really works makes a difference, at least for lower level grad classes. :) and trying to present groups as the widely useful abstractions they are instead of just a cute self contained theory makes a difference.

Interesting to note we haven’t got a text book for these classes just lecture notes and a number of text books recommended if we want additional presentations.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#133

“Why is it that no one has undertaken the task of cleaning the Augean stables of elementary differential equations? I will hazard an answer: for the same reason why we see so little change anywhere today, whether in society, in politics, or in science“ I see a lot of parallels with the Physics department and I think the reason is much more depressing. Both fields embrace a sort of masochism and active desire to keep…

> Both fields embrace a sort of masochism and active desire to keep knowledge impenetrable b/c it acts as a mechanism to feed out the dummies.

Did you go to a top university? And did you study physics in grad school? I find this statement amusing given how easy the undergrad curriculum was compared to grad school physics.

In my undergrad, physics was challenging only in that you needed a good command of the mathematics. If you had that, the actual instruction (and textbooks) were of average difficulty.

But again, experience may vary from university to university. Certainly I can see professors who could have made it much tougher if they wanted to.

As for the rest of your comments in this thread: Sorry, but to me this is another HN thread where people insist it can be taught better, and teachers are being irresponsible in not finding such approaches, but with very little actual proof that it can be as good as imagined. It's not like you have concrete examples of better pedagogy to pointed out.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#134

> What can we expect students to get out of an elementary course in differential equations? I reject the “bag of tricks” answer to this question. A course taught as a bag of tricks is devoid of educational value. One year later, the students will forget the tricks, most of which are useless anyway. That's exactly how I was taught differential equations 20 years ago. And as expected I have totally forgotten all of the…

The further I got into maths (not very far mind you, but I think I at least did a few differential equations,) the more it felt that maths really was just a bag of tricks, moreso at the advanced end.

* Keep deriving circular functions until they cancel out. * Completing the square * Use the quadratic formula to solve degree-2 polynomials ... No formula for degree-5 or higher. * Use the Laplace transform here... for reasons...

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#135

“Why is it that no one has undertaken the task of cleaning the Augean stables of elementary differential equations? I will hazard an answer: for the same reason why we see so little change anywhere today, whether in society, in politics, or in science“ I see a lot of parallels with the Physics department and I think the reason is much more depressing. Both fields embrace a sort of masochism and active desire to keep…

> The system acts an an informal IQ test

Undergrad textbooks in Physics may be somewhat challenging. But the graduate texts (at least in theoretical Physics) tend to be MUCH harder, especially if your undergrad degree didn't include several courses of abstract algebra and topology.

Ideally, physicists should have Geometric Algebra (Clifford Algebra) as part of their undergraduate classes. But at least when I went to Uni, there was no space in the undergrad tracks for this level of math.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#136
post #66

Earlier quoted context omitted.

I don't know why you're catching downvotes, I think you're completely right. In my engineering curriculum in some cases the teachers were openly hostile to students that had a hard time understanding the material. Professors of undergraduates don't seem to think from the undergraduate perspective. Most undergrads have only ever known school, and are just following directions while fumbling their way to their first in…

I mean, have you ever taught a class? Do you know how it feels when we make sure a topic is covered both in class and recitation with plenty of time for questions and the students still stuff it?

No, I've never taught a class, so it's possible that the experience of teaching as a professor would irrevocably change my opinion. However, I have spent a lot of time tutoring math and directing bands and choirs, so I'm familiar with the frustration that comes from explaining concepts and then assigning necessary work with plenty of time to do it and then having people still show up unprepared.

I believe that there is a negative feedback loop in the current model of schooling: unprepared students produce jaded instructors produce unprepared students. The big problem with the current lecture method is that any interruption of the momentum of the course for the students' own personal benefit comes with a social cost, so it's better to just shut up and pretend you know what's going on. Furthermore, many lectures build on themselves, so if you misunderstand a concept at minute 3, by minute 20 you're checked out and by minute 50 you're clock-watching. That's why so many math lectures are silent with the exception of the occasional interjection from a star student.

Combine this with the fact that most students are insufficiently prepared for course material in the first place and you end up with modern STEM college: kids who don't get the material slogging through piles of completion-based assignments and exams and putting in the minimum amount of work to get the degree, after which most get the exact same job they'd have gotten if they'd worked harder anyway. They're almost incentivized against deep examination of any one topic, because all time spent working on one assignment incurs a cost against other assignments, or against leisure.

There are so many issues with the way education works at scale in the first world that going down any pathway would take a thousand words, so I'll sum up by saying that I believe that you have a point, and I also believe that the majority of undergraduates are underprepared, entitled, have underdeveloped work ethics, and lack both the discipline and drive necessary to really get something out of their education. However, I still think that the extreme burn-out classes cause more detriments to higher education than they bring as a whole.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#137
I had him for second term calculus, which was the first math course I took in college. So I get to listen to him speak it in my minds eye —- his voice is unforgettable. He was a great teacher. 2. I have an interesting take on this subject. I became an engineer at 50. Out of personal choice. What I found was that engineering had changed and what mattered was your savvy in manipulating expensive programs on the computer. In those programs, differential equations were solved numerically. No one even thinks about solving them any other way. There isn’t any time.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#138
post #67
post #66

Earlier quoted context omitted.

I don't know why you're catching downvotes, I think you're completely right. In my engineering curriculum in some cases the teachers were openly hostile to students that had a hard time understanding the material. Professors of undergraduates don't seem to think from the undergraduate perspective. Most undergrads have only ever known school, and are just following directions while fumbling their way to their first in…

> In my engineering curriculum in some cases the teachers were openly hostile to students that had a hard time understanding the material. While there's no excuse for it, I think faculty see so much apathy on such a regular basis that sometimes it's easy to mistake sincere struggle for a lack of desire to engage. For precisely that reason, I try very hard to recognize and reward my students who are willing to take th…

> This is a beautiful description. I know as a teacher that I try to communicate this to my students, but also that I surely fail much more often than I succeed.

Thanks. There's an element of hopelessness in trying to explain the immensity of human knowledge to someone who's lived their entire life captured by mandatory schooling. It's just not an interesting thought to most of them. Their worldview has been so artificially limited that attempts to explain the limitations of their circumstances just appear to be more limitations. "Guys, there are more than six hundred thousand mathematicians working right now in the US, and they're working with concepts first thought of as long ago as 3000 BC and maybe earlier!" "Okay, will that be on the test?"

> Isn't it better if that's in the classroom rather than on the job?

If only we were having this conversation in a bar instead of a text forum. That's a huge question and it's clear you're actually interested in talking about your thoughts on it. It's also a subject that interests me.

When you say:

> But those topics have to be, or are believed to have to be, understood to be successful in the field,

I think that's where the big disconnect comes from. What's the point of school? Is it to know enough to be useful at a job, or to plumb the depths of knowledge? Is it some third thing? Ask any recruiter and they'll tell you the new hires aren't prepared to actually do anything useful, and ask any advisor and they'll tell you the new graduate students aren't prepared to actually do anything useful, so we can at least conclude that there's some kind of disconnect going on. Students spend thousands of hours and hundreds of thousands of dollars doing something that does not actually adequately prepare them for what people want them for.

I have a hundred different ideas about how to address this. One thought I've been mulling over recently is that a redefinition of grades is in order. From essay that we're commenting on:

"My colleague’s error consisted of believing that the more testable the material, the more teachable it is. A wider spread of performance in the problem sets and in the quizzes makes the assignment of grades “more objective.” The course is turned into a game of skill, where manipulative ability outweighs understanding...

In an elementary course in differential equations, students should learn a few basic concepts that they will remember for the rest of their lives, such as the universal occurrence of the exponential function, stability, the relationship between trajectories and integrals of systems, phase plane analysis, the manipulation of the Laplace transform, perhaps even the fascinating relationship between partial fraction decompositions and convolutions via Laplace transforms. Who cares whether the students become skilled at working out tricky problems? What matters is their getting a feeling for the importance of the subject, their coming out of the course with the conviction of the inevitability of differential equations, and with enhanced faith in the power of mathematics. These objectives are better achieved by stretching the students’ minds to the utmost limits of cultural breadth of which they are capable, and by pitching the material at a level that is just a little higher than they can reach."

At the undergraduate/introductory level, the only important question is "what awareness do you have of the breadth of this field, and what mastery do you have over the concepts that most agree are its "most fundamental"? You and I both agree that class is a "playground", and any "grade" is in fact meaningless. Rather than assigning As, Bs, Cs etc. as a percentile of subjective completion of arbitrary problem sets, As-Fs should be assigned at the discretion of the instructor as a holistic assessment of oral and written examination, completion of problems and problem sets, participation in the class, and general wisdom.

Students would of course resist this. They want to be graded on impartial, meaningless criteria. That's how they're taught from third grade, and it's the method that allows for the least possible interaction with the material. The only reason they want these grading criteria is so they can plan to spend as little time as possible on the class. This method of approaching learning simply has to be broken at every level of education. You shouldn't even have a GPA until college.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#139
How math relates to the physical world is not at all clear. Like yes 2 apples clearly makes sense, but non physical quantities like 10^241 of anything start to break down the relationship.

It’s not the abstraction that gets me usually, it’s the lack of an explicit relationship between math and physics. I’m sorry but personally I am not satisfied by what I learned in my math and math/science classes on this. It started for me day 1 of high school physics and I’m now graduating in 1 month in undergrad applied mathematics.

I felt reinforced when I read that Plato clearly delineated the two “realms”. I was hopeful a single math teacher would discuss this idea for one lesson, but it never happened. Plato was a champion of math who recognized the division.

I’m not one of those disbelievers in complex numbers or anything like that, but if some model formulates precise physical scenarios, we should be able to have ample cross-over language. Even the explanation for why honeycombs have six sides: there is always some kind of fumble from going from the mathematical reason to the physical reason. It’s the paradigmatic example of mathematical explanations for physical phenomena, and between two heavily studied fields, and yet we fumble it continually. What is it about the mathematical hexagon which determines the physical honeycomb? These questions are at the height of philosophy of mathematics, e.g. Mark Colyvan, yet are still disputed and we act like it’s all so obvious. I get it works, but don’t tell me it’s not mysterious, because 6 years in now I’m not at all satisfied and have little confidence it will be mentioned in future math/science classes.

Re: Lessons I wish I had learned before teaching differential equations [pdf] (1997)

#140

Earlier quoted context omitted.

I'd say that the Fourier Transformation doesn't belong in the calculus program at all. It should be taught in linear algebra, where it does not only make sense, but is a non-trivial example of application that the textbooks have so little of.

Why should it be in linear algebra? You mean as in doing linear algebra with functions in infinite-dimensional spaces? What I recall mostly (not) learning from linear algebra were various classifications of matrices and their properties (which made very little sense to me at the time too). I'm not exactly sure where FT should belong in the math syllabus. It's heavily related to trigonometry of course but it is an int…

In fact, there is a lack of linear algebra in infinite-dimensional spaces on the general curriculum, and it is an important subject for physics and a few engineering areas besides the relevance for mathematicians. It wasn't clear to me how the dependency between calculus and algebra was supposed to be, but your comment makes it crystal clear.

The discrete transformation is quite fitting for finite-dimensional algebra, and honestly I can't understand how anybody every thought teaching the continuous transformation first and the discrete one never was a good idea. The only explanation is that since everything is thrown on the calculus package without any consideration, there's only time for one, so people kept the most general one.

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