Sal Khan responds to critic

By Valerie Strauss

A guest post I published Monday critiquing the Khan Academy received a great deal of response, including the following e-mail from Salman Khan, founder of the academy. As math was not my subject in school, I don't know who is right but would love to hear from mathematicians out there.

For those who may not know, the Khan Academy is essentially a library of more than 3,300 videos on subjects including math, physics, and history that are intended to allow students to learn at their own pace. Questions were raised about the quality of some of the math videos in the Monday post as well as in others elsewhere on the Web.

Below is Khan’s e-mail to me, which I shared with the author of Monday’s post, Karim Kai Ani, a former middle school teacher and math coach who is the founder of a company called Mathalicious. He said Khan is wrong. This won’t be the end of the debate.

Here’s Khan’s e-mail:

Hi Valerie,

We here at the Khan Academy appreciate a public discourse on education and really encourage as much feedback as possible.  We believe that we are in the early days of what we are and feedback will only make that better.  I agree with you that no organization should be upheld as a magic bullet for education woes.  We have never said that we are a cure-all and think we have a lot to do just to fulfill our potential as a valuable tool for students and teachers. Unfortunately, some of the headlines on articles are more grandiose, but we have no say in this.

In your previous post, you talk about the value of experiential learning versus lecture-based.  We agree 100% with you; that is what KA is about too--allowing classrooms to be more interactive and experiential.  See this video: http://www.khanacademy.org/talks-and-interviews/v/ideal-math-and-science-class-time.

We are also running project based summer camps.

With that said, there have been some major errors on your blog.  In particular, Karim’s corrections are very incorrect (I encourage you to seek out an impartial math professor). 

 Slope actually is defined as change in y over change in x (or rise over run).

 Karim’s definition is actually incorrect. Slope is not just a rate between two variables. It is how the variable plotted on the vertical axis changes with respect to the variable plotted on the horizontal axis (or “rise over run”). For example, if price were on the x-axis and memory on the y-axis, then Karim’s “how the price of an iPod changes as you buy more memory” would not be slope (it would be the inverse).

And, yes, slope is often unit-less (especially when measuring the slope of say the surface of a mountain which is where the whole idea comes from — you are dividing a distance by a distance so the units cancel).

I walk through this in a video at: http://www.youtube.com/watch?v=TNaQJjLAhkI

I also think you might misunderstand our “business model.”  Unlike Mathalicious which is for-profit (and if it does well, Karim will become very wealthy), Khan Academy is a 501c3 not-for-profit.  I take a salary from it that is approved by the board, but I do not own it (no one does).  It can never IPO or be sold.  It is a public charity.

Let me know if you’d like to chat further.

regards,

Sal