Interviews: Ask Lead Developer Ben Kamens About Khan Academy

Ben Kamens spent over 5 years at Fog Creek, eventually working his way up to VP of engineering. However, after watching one of Salman Khan's talks he started to volunteer his time at Khan Academy, and is now the lead developer. In-between providing a free world-class education for anyone anywhere, he's graciously agreed to answer some of your questions. As usual, ask as many questions as you'd like, but please, one question per post.

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[GeneralSecretary]

It seems to me that the problem with online education is being able to prove what you have learned. I can learn Calculus online at Khan Academy or at my local community college. I'll probably learn Calculus better at Khan Academy and for less money. But, I cannot use that knowledge to get a degree nor would I have any other way of proving my knowledge to other schools or potential employers. Do you have a solution to this problem?

Where are all the CS courses?

[Anonymous Coward]

Where are all the "traditional" Computer Science courses? I'm not asking about the "interactive manual" type courses like how to do loops in Python - there are a ton of materials about that all over the web. I'm asking about theoretical computer science, such as Turing completeness, Chomsky hierarchy, abstract data types, compiler design, that kind of stuff which is the backbone of a university computer science education.

The reason I'm asking is not to diminish the value of hands-on courses, but because many (including myself) were not able to get a "traditional" CS degree, coming into programming jobs from other disciplines (or no degree at all) and are largely self taught. Self teaching is great when it comes to practical stuff early on, but once you move on to more senior roles you start feeling the gaps of not understanding the theory behind your tools, design, and implementation, as much as you should.

Why videos?

[magic maverick]

One of the big things about Khan and other massive online course systems is videos. Yes, videos. E.g. I once saw this 5 minute video explaining why dividing anything by zero was not defined. Rather than, plus infinity. I summarized it as:

Dividing by zero is undefined. Why? Well, let's divide by 1 by really small positive numbers.
1/0.1 = 10
1/0.01 = 100
1/0.000001 = 1000000
So, it looks like, 1/0 could be infinity. But positive infinity.
Because, look at what happens when we divided by really small negative numbers
1/-0.1 = -10
1/-0.01 = -100
1/-0.000001 = -1000000
So, maybe 1/0 should be negative infinity. But that doesn't match what we saw above. It can't be both, and it makes no sense to give it an arbitry value as that wouldn't work with the rest of mathematics.
Therefore, undefined.

OK, so the question is: why videos? You are cutting off most of the world's population who do not have access to decent Internet and thus can't download and watch all these videos. If you provided text (even if just a transcript along with some screenshots where necessary) you would be able to reach a much bigger audience, including those who could benefit most.