Apparently Salman Khan has been working on his been working on his website full-time since September 2009, but I'm just hearing tell.
Here he is on the question of how he knows the Khan Academy is effective:
My background is in math, computer science, and investment management, so I think you can imagine that no one is more obsessed with data and analytics than me. The chart to the right is provided by YouTube. It can be used to determine if and/or when viewers' attention falls off at a certain point of a video. I can then go back and try to identify (and possibly fix) what happened at that point in the video. This next chart shows the average (black line) progress of a cohort of 30 rising 8th graders on the Khan Academy software over a 6-week period. The horizontal axis is "days working on the site" and the vertical axis is "modules completed." The green lines show one standard deviation above and below the mean. This chart exemplifies both the level of data we are capturing and also highlights the importance of individualized, self-paced instruction and real-time assessment. The purple line shows a student who may have been deemed "slow" by traditional assessments because she was more than one standard deviation below the class average after working on the site for a few days. The reality is that she just needed more time ramping up on negative numbers than the other students in the cohort. Once she was given the chance to become proficient on that concept, she raced forward and ended up being one of the top students in the cohort.
More than the data, however, it is the anecdotal evidence from users that has convinced me to quit my job and make this the focus of my life. I receive hundreds of letter and comments a week. Many are simply notes of strong appreciation, but several reach the level of being genuinely inspiring. Here is a letter I received from a YouTube user in September 2009 (I bolded some of the text):
No teacher has ever done me any good--this may sound harsh but I mean it quite literally. I was force fed medication to keep me from talking and chastised for not speaking out when called on. Where I am from blacks are not welcomed with open arms into schools--my mother and her sisters had to go to a small shack two hours from home when they went to school. About five years ago my family collected enough money to move from where i was born, so that I could have a chance at having an education and living a real life. But without a real mastery of elementary math I was slow to progress.
I am now in college and learning more than I ever have in my life. But an inadequate math background has been holding me back. I found the Kahn Academy in June of 2009, right after I completed Math 141 ( a college algebra course). I have spent the entire summer on your youtube page. And I just wanted to thank you for everything you are doing. You are a Godsend. Last week I tested for a math placement exam and I am now in Honors Math 200. No question was answered incorrectly. My placement test holder was so impressed by the breadth of my knowledge of math that he said I should be in Linear algebra.
Mr. Khan, I can say without any doubt that you have changed my life and the lives of everyone in my family.
I wish you and the Khan Academy the best of luck,
How did you get started?
My uncle's family visited me in Boston after my wedding in the summer of 2004. At some point during the trip, my Aunt told me that her daughter (my cousin) was having trouble with "unit conversion" which was not allowing her to be placed in the more advanced math track for 7th grade. Nadia was clearly a very bright girl, so I made a deal with her. I'd remotely tutor her for an hour after work as long as she was willing to do any extra work I gave her.
I began remotely tutoring Nadia in August of 2004. She was in New Orleans--where I also grew up-- so we used a telephone to talk and Yahoo Doodle as a shared notepad. Nadia ended up catching up and getting ahead of her class so I started tutoring her brothers, Arman and Ali, as well. Eventually, word got around and I was remotely tutoring and handful of cousins and family friends. Scheduling around my work, their soccer practice, and the different time zones became a little ridiculous, so I started to make YouTube videos for them to watch in their own time, at their own pace.
It didn't take long to see that other students (including adult learners) were hungry for videos like these so I kept going!
How did you have the time to do this while working full-time?
My wife was doing her residency--in internal medicine-- from 2005 to 2008, so there were many nights/weekends where she was working and I would have felt guilty doing anything less productive. I also try to watch very little television. On top of that, I was working at an investment fund that had me working 5am to 2pm (we were working East Coat hours from California) so my afternoons were free (although I did go to bed at 9).
How are you funding/making money off of this?
I quit my day job as of September 2009 to work on this full-time and was digging into my savings until recently. In May, some generous individuals have given large enough gifts for me to take a salary for the time being. I could be aggressive with advertising on the site, but I don't want to do that until I have to. I am speaking to some foundations that might enable Khan Academy to get to the next level. If you know of potential partner foundations who would agree that there is no better way to educate and enlighten the world, they shouldn't hesitate to email me (sal 'at' khanacademy 'dot' org) :)
Khan Academy is a IRS-recognized 501c3 not-for-profit organization. My goal is to make it self-sustaining in the next five years.
Are you interested in turning this into a business? Maybe with some VC funding?
I've been approached several times, but it just didn't feel right. When I'm 80, I want to feel that I helped give access to a world-class education to billions of students around the world. Sounds a lot better than starting a business that educates some subset of the developed world that can pay $19.95/month and eventually selling it to some text book company or something. I already have a beautiful wife, a hilarious son, two hondas and a decent house. What else does a man need?
With that said, if you are a social venture capitalist and are looking to deploy capital with the highest possible social return per dollar invested, we should talk. I think you'll find that there is no more measurable, scalable and high impact way to educate the world.
Did you do all of the videos?
As of today (6/10/2010), yes. All 1400+ videos have been made by me. Volunteers have begun to translate the videos into other languages. Here is the Khan Academy en espanol. Hope to have other channels in the not-too-far-off future!
What topics do you plan to cover?
My goal is to cover everything. Yes, everything! Most of k-12 math has already been done (although I do need to make 20 or 30 more elementary math videos). My goal really is to keep making videos until the day I die (which will hopefully not be for at least another 50 or 60 years). Should give me time to make several tens of thousands of videos in pretty much every subject.
What is the long-term goal for the Khan Academy?
I see Khan Academy becoming the world's first free, world-class virtual school where anyone can learn anything--for free.
The videos are just part of the vision. We hope to build out the adaptive software to cover all the topics that the videos cover. We also intend to develop simulation games to give more nuanced and applied understanding of concepts.
SAT prep, too
We have done all 8 math practice tests (432 problems) in "The Official SAT Study Guide" by the College Board (which you should buy) in the 100+ videos below.
We recommend that you buy the book and take at least one practice test (3 math sections) per week during each of the 8 weeks prior to the exam. In the earlier weeks, you should focus on comprehending and working on every problem. In the second four weeks, you should focus on speed and eliminating careless mistakes (although you should still try to do any problems that you didn't get to). After grading each of your exams, watch the corresponding video below.
If you have the self-discipline to take the practice tests, review your problems and watch the videos, we think you will be as prepared as anyone. You should view these videos as your on-demand personal tutor.
If you need to review (or learn) underlying mathematical concepts covered on the SAT, we have over 800 videos on general math topics in our video library.
I just watched the solution to question 17 on page 412 and had a major duh moment.
Which is exactly what I should be having -- but am not having with the SAT prep books, which frequently make simple problems seem more complex, at least to me.