
New Khan Academy Exercise Framework Is Live - rubergly
http://ejohn.org/blog/khan-exercise-rewrite/
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aik
Good stuff -- the simplification of the code is exciting for sure and is bound
to encourage more to join to create more problems (it has for me!)

One question/problem/concern: Just for fun I tried out the "Linear equations
1" problem section.

So I just got the problem "Solve for x: 9x = 6". Naturally I could answer 2/3
and would expect a happy face, however I decided to answer 6/9, also a true
answer, to try the system out. I was received with a sad face (incorrect
answer). But, why? The solution is actually true -- it's just missing the
artificial target the website has set. The site doesn't explain that it wants
the lowest denominator (just "Solve for x"). I would think this to be
misleading -- what do you think? How could the proper lesson be enforced here?
How and why should students assume 2/3 is right and not 6/9? There's a danger
here of students looking for the answer the system wants (extrinsic motivator)
rather of what they have found to be right and then denied the satisfaction.

I would expect a happy face with 6/9. It seems to me that the problem should
allow multiple answers -- or for the goals of the lesson to be more detailed
(and perhaps include an explanation/recommendation after the fact of what the
problem is really asking for).

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rubergly
We're very aware of this kind of issue; don't worry. We're currently working
on A) displaying information to let a user know what kind of format an answer
requires (for the problem in question, we require a reduced fraction written
as 'A/B') and B) providing more specific feedback than just 'wrong' or 'right'
for cases like this when an answer can be mathematically correct but not
accepted for the specific problem. Thanks for pointing this out and reminding
us of its importance!

~~~
kenjackson
What would be cool is if you guys integrated Mathematica into Khan Academy.
There is that new document format they introduced. For math it would be super
useful to have the ability to really play with formulas directly in Khan
Academy.

~~~
capnrefsmmat
Mathematica may be overkill -- I suspect they'd just need something for basic
symbolic manipulation, to reduce answers. In any case, a web-based mathematics
system already exists; Sage can be run in a browser, and it integrates a
number of useful mathematical features with Python:

<http://sagemath.org/>

~~~
ylem
sympy would be another alternative--it's light, it's python, but has a web
interface and has a very active community.

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rubergly
The exercises are live at <http://www.khanacademy.org/exercisedashboard>.

We're really proud of the improvements we've made to the framework and how
much easier we've made it to add new exercises; if you're interested in
contributing, please fork the code at <https://github.com/khan/khan-
exercises>.

We're working as fast as we can to fix any bugs that pop up, so we'd
appreciate reporting any issues using the "Report a Problem" link at the
bottom of every exercise page.

~~~
zerohp
I'm a 33 year old self-taught software developer, that originally skipped
college, who is starting at a local community college this fall with plans to
transfer to Illinois for Computer Engineering.

I can't express how much your team and Mr Khan have helped me. In June I spent
one to two hours a day watching videos and completing exercises to prepare for
my schools placement exam. Starting from the beginning, not only did I refresh
my memory but also learned essential concepts that my high school education
did not cover. Thanks to your site I placed at the highest level my school
will place an incoming freshmen for mathematics.

I'm looking forward to finishing off the last 4 exercises and hope to see more
soon. I would be very nervous about both working and going to school full
time, during my first year, without Khan Academy helping me get a head start
before the semester starts. The high quality lectures and exercises you
provide are fantastic for someone like me who may not have the ability to
attend office hours and tutoring as much as a conventional student.

Thank you for all that you're doing. It's revolutionary.

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solutionyogi
From the source code:

// Yuck! There is no god. John will personally gut punch whoever thought this
was a good API design.

[https://github.com/Khan/khan-exercises/blob/master/khan-
exer...](https://github.com/Khan/khan-exercises/blob/master/khan-
exercise.js#L180)

:)

~~~
jeresig
Heh yeah, the Mathjax API is rather awful. Tons of separate file requests,
configuration is only designed to work in inline script tags, and other
ugliness. We've been experimenting with MathQuill - it's way faster and much
more lightweight. Unfortunately it doesn't have all the features that we need
otherwise we'd switch right away.

<http://laughinghan.github.com/mathquill/>

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tnorthcutt
John (and others working on Khan Academy),

I've known about Khan Academy for 6 months to a year. Recently, however, I've
started to become MUCH more interested in it. I'm starting to feel a strong
pull towards doing things to help people in my local community - specifically
through education. I think there's a lot of potential for Khan Academy to play
a significant role in that. I haven't started something concrete yet, but
wanted to take this opportunity to thank you and everyone else working on Khan
Academy for what you're doing. I think it's extremely important and valuable
work.

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qq66
It's great that Khan Academy has a 100x engineer even though some have said
they don't need one. This can be a 100-year project and having a solid
technical foundation will allow it to become one.

~~~
jpulgarin
Does 100x, mean full time? Khan Academy has various full-time engineers.

~~~
mnutt
I assume that is referring to Paul Graham's assertion that a good developer
isn't just a little better than an average developer, but is instead orders of
magnitude better.

~~~
asg
This assertion (among many other gems) was originally stated in the Mythical
Man Month, by Fred Brooks, published in 1975.

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neilk
If I understand correctly, some templating transforms the <var>s, etc., into
JavaScript. Why not write the JS as a regular program? The syntax you have
doesn't seem dramatically easier than just ordinary JS and has to be a bit
confining.

Is it really that repetitive, or does the code need to be expanded in
different ways in different contexts?

~~~
bbq
I'm wondering the same thing. I imagine with CoffeeScript it could look very
nice.

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pbhjpbhj
Supposing many more problems sets are added, how're they going to manage this
proliferation.

My 6yo has been using it for a little while - I've not investigated it deeply
but it seems that videos and exercises are quite tightly paired. Having many
more exercise [overlapping] sets would make it hard to choose which to do.

It seems the whole system wouldn't work as well with an open access method of
submitting exercises, so what's this leading towards?

Aside: I think the scratch pad could be vastly improved. When my 6 yo is doing
addition/subtraction trying to write out a number line on the scratchpad is
harder for them than doing the sums, it gets in the way. Of course he uses a
pieces of paper instead but that seems a bit silly. They could integrate a
number line drawing tool, ...

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tybris
Almost makes me want to go to school again.

~~~
alanfalcon
It's available to anyone and everyone, even you! Right now!

