Why? Drawing from my experience learning
some technical material, I will
give some candidate answers:

(1) Content. From what I've seen of MOOCs
in some areas where I know some things,
usually the content looks poor just on
the subject itself and/or its presentation,
i.e., too many of the lectures are just poorly
done in any common sense of good lectures.
E.g., start in the upper, left corner of
the board and write clearly, clearly enough
so that a student can take essentially perfect
notes.

(2) Purpose. Commonly the courses do not have
a sufficiently clear and meaningful purpose
for enough candidate students.

E.g., why study calculus? What MOOCs provide
a really clear answer meaningful even to
most of the people who consider a course in
calculus?

E.g., why'd I study calculus?
In., in grades 1-8 I got dumped on by the
teachers; those teachers wanted to
teach to the girls with their
better handwriting, better verbal
talent and skills,
better clerical talent,
better insight
into fictional literature, and much
better classroom decorum. I
wanted, strongly beyond belief, to
know how things worked, and the
girls were little masters at knowing
how the teachers worked!

In grade 9 I discovered I could
do math, i.e., algebra and fairly easily
could lead the class. Essentially all the
girls in the class, all of whom had
effortlessly blown me away in grades 1-8
now were struggling while I was having
a great time, easily.

I got sent to a
math tournament. That success continued
in grades 10-12. In the 11th grade, I
saw the same for physics -- could usually
have my head down in class, resting, and
still be one of the best students in the
class -- of mostly 12th graders,
three of whom went to Princeton and
ran against each other and some fourth
sucker for President of the freshman
class. I got sent to an NSF math and
physics summer program.

So, in college, I was hot to go in
math and quickly went through the
course catalog and planned all the
math courses I would have for all four
years. I really liked math!

But to save money, I did my freshman college
year at a state school, inexpensive, I
could walk to. They forced me into a
course in college algebra beneath what
I'd already done in high school
(by far the best in the city, e.g.,
the three guys who went to Princeton;
MIT came recruiting; a guy I beat in
a shootout at the board in trig class
went to MIT). A girl told me when
the tests were, and I showed up only for
those.

But, I knew that as a freshman
I was supposed to be learning
calculus and was torqued that I
was not. So I got the recommended
calculus book and dug in. In grades
9-12 I'd learned mostly just from the
book so also was able to do well working
through the calculus book, totally
independently.

I did well: E.g.,
I had quite nice college board scores,
especially in math and physics,
so, the next year (we had a little more
money) I got into
a good four year college.

So, where to start there in math?
Okay, I asked to start with just their
sophomore calculus. They said that
they couldn't give me credit for
first year calculus, but that was totally
fine with me. The text they used was the
same as Harvard used; it was good.
I did fine -- made As, loved the material,
had fun, didn't work at it very hard.
Right: I was a math major but never
really took a course in freshman calculus!

Also blew away everyone in their freshman
physics course -- first test had four
questions; I got all four; no other
student got more than two; tree counted
as 100; so I got 133; and I never missed
anything for the rest of the semester
so ended up with 33 points over a perfect
score. The second semester, missed only
one test question.

Went on and got honors
in math, got a Ph.D. in applied
math (stochastic optimal control),
have had math much of my career, and now
have some original math I derived as the
crucial core technology for my search engine
start up. Lesson: I've had a
purpose in mind learning math.

So, I did learn calculus, just on my own
for freshman calculus. So, why? Sure:
(a) Motivation. I really, really, really
wanted to know the material, not just a little
bit but a lot. (b) Resources. I had plenty
of time to do the work. (c) Preparation.
The four years of math I took in high
school gave me about everything one could
want in prerequisites for calculus.
(d) While I didn't know much about just
what I would do with calculus or math
after college, I did believe that they
should help my career, and I knew that,
for math, calculus was one of the biggies.

Okay, for the MOOCs, if
have (a)-(d) and some good materials, then
lots of students should do well.
If are not having many students are doing well,
then look first at (a)-(d) and the
materials. From what I've seen,
too commonly the course materials
are not very good.

E.g., for calculus, from what I've seen,
it appears that the courses want to
imply the a person can learn calculus
easily as a spectator (sport) watching videos
instead of doing the work studying good
materials, say, a good text. I doubt
that many students could learn calculus
as a spectator sport.

There really can be opportunities for
people to learn outside a classroom,
and online materials can help.
But need good materials, likely including
a good, traditional text book, and
also need, say, (a)-(d) above.

By the way, as a math grad student, I
taught calculus successfully. As an
MBA prof, I taught more in applied math
successfully. In my career, I continued
to learn on my own: E.g., for some weeks
I carried Blackman and Tukey, The Measurement
of Power Spectra to dinner at a seafood
bar in Silver Spring, MD, and then one week,
mostly on my own without my company
knowing about it,
wrote some corresponding software which
was a big help in our company winning
a competitive software development
contract -- my work on power spectra
estimation had in effect given our company
sole source.

Lesson 1: Math can
make money.

Lesson 2: It is possible
to do the work of math making money
mostly via independent study.

Lesson 3:
I doubt that any of the MOOCs will
cover how to measure power spectra, say,
with the fast Fourier transform (FFT)!

How about a continuous
time, discrete state space Markov process
subordinated to a Poisson process?
Make money with that? Did that once.
Covered well in a MOOC? I doubt it!

I used to look at MOOCs, wanted to learn
more about,
say, stochastic processes in continuous
time, say, like in Gihman and Skorohod or
Lipster and Shiryayev
or
Karatzas and Shreve.
Gee, I didn't find much!

There is high irony here:
This is Hacker News, and my view is that
nearly all the learning crucial for the
current US information technology
industry, especially the software part of it,
has been from essentially just independent
study. So, the irony is that the
readers of Hacker News should be
about the best audience for MOOCs.

E.g., for a while in my career,
when I was fairly deep into computing but
before I'd ever had a course in
computing or computer science,
I taught several sections
of computer science at Georgetown
University. Later in grad school,
I was pushed to take a course in
computer science -- not much past
what I'd taught at Georgetown! At
one point, sure, the course tried
to cover quicksort. Okay, worthwhile
for such a course!
But I'd long since learned quicksort,
heap sort, Shell sort, bubble sort,
merge sort, etc. from some original papers and
Knuth's The Art of Computer Programming,
programmed all those that were in-place sort
algorithms, compared their performance,
programmed some special purpose versions,
etc. So, during the course, I just
watched and smiled. Gee, they neglected
to mention that in the bit reversed
permutation from some of the
versions of the fast Fourier transform,
Shell sort does nothing at all until
the last pass at which time it runs
in O(N^2)! Gee, why didn't they
mention that one!

Lesson: It's possible to
do well in computing and computer science
with independent
study.

Surprise: One of the profs in that
course didn't like me and gave me a grade of
C. I appealed to the department,
pointed to some code I'd submitted
in my application to the department,
the code I'd written to schedule the
fleet at FedEx, the code I'd written
for power spectral estimation, etc.,
and the next year that prof was gone!

Lesson: If the Hacker News audience is
not doing well with MOOCs, then blame
the MOOCs, not the students!