What follows is an open letter to those friends of mine -- and superstar math educators around the country -- who take these positions. I don't think they're wrong. But they are short-sighted. Read on to find out why.

Friends--

At the risk of stating the obvious, you aren't run-of-the-mill math teachers. Of course you can envision--indeed, give daily--lessons that are more in-depth, challenging, authentic, inquiry-based, etc., than Khan Academy. Indeed, I would be shocked if you couldn't.

But that's not the question. Khan Academy wasn't created for yourstudents. It was created for kids whose teachers, in many cases, don't even know the content, much less how to present it clearly or explain it well. Have you been to the elementary schools in my district? Because (as many of you know) something like half the freshmen who come to my school can't use a protractor to measure an obtuse angle --- they tell me it's 61 degrees or something cockamamie like that --- and they TOOK A TEST to get into my school (indeed, the cutoff score for my school is over 800 out of 900 possible points; we rejected more than 2000 kids out of the 2400 who applied). Those kids will get more effective instruction from Khan Academy than they can get in a regular classroom, because right now they aren't getting effective instruction in their regular classrooms, period. (I'm not blaming anyone in particular here, simply making the tautological claim that instruction that doesn't result in kids being able to do the things they are being instructed in how to do is, by definition, not effective.)

It works for other kids too: my daughter was far ahead of her class last year, and for the first half of the year did worksheets in the back of the room. For the second half of the year, she and two friends got to go on Khan Academy and pick their own lesson every day, and she grew more (as measured by NWEA/MAP scores) in that semester than in the previous 1.5 years combined. And she got about a quarter of the way through a standard Algebra I course.

Finally, I'd say this--about flipped classroom stuff generally and KA in particular. Right now, I'm cooking up a pot of Cincinnati Chili (mmm...can you smell it?). It's delicious, nutritious (yay low-fat turkey!), and my kids love it. But there's a diner down the street from my house, and any day I want, I can go there and get a reasonably tasty, reasonably healthy meal at a reasonably low price. And so every week or two--when I'm too tired, or we have nothing in the refrigerator--we go there for dinner. It's not Tru, or Topolobampo, or any of the other great restaurants Chicago is known for--but it's a reasonable way to get fed once in a while. I think KA and other online videos are like that: not as good as the best (although maybe if you watch the first lecture of the Udacity physics series, on Eratosthenes' measure of the circumference of the earth, you'd be surprised). But KA delivers reasonably clear, correct instruction to people who might not otherwise have access to it. Friends who have expressed skepticism about the "All Khan, All the Time" approach: I agree wholeheartedly. Let's give our kids a balanced diet of different kinds of instruction and different ways of thinking about problems. But I don't think that's a reason to trash on Khan altogether.

At the risk of stating the obvious, you aren't run-of-the-mill math teachers. Of course you can envision--indeed, give daily--lessons that are more in-depth, challenging, authentic, inquiry-based, etc., than Khan Academy. Indeed, I would be shocked if you couldn't.

But that's not the question. Khan Academy wasn't created for yourstudents. It was created for kids whose teachers, in many cases, don't even know the content, much less how to present it clearly or explain it well. Have you been to the elementary schools in my district? Because (as many of you know) something like half the freshmen who come to my school can't use a protractor to measure an obtuse angle --- they tell me it's 61 degrees or something cockamamie like that --- and they TOOK A TEST to get into my school (indeed, the cutoff score for my school is over 800 out of 900 possible points; we rejected more than 2000 kids out of the 2400 who applied). Those kids will get more effective instruction from Khan Academy than they can get in a regular classroom, because right now they aren't getting effective instruction in their regular classrooms, period. (I'm not blaming anyone in particular here, simply making the tautological claim that instruction that doesn't result in kids being able to do the things they are being instructed in how to do is, by definition, not effective.)

It works for other kids too: my daughter was far ahead of her class last year, and for the first half of the year did worksheets in the back of the room. For the second half of the year, she and two friends got to go on Khan Academy and pick their own lesson every day, and she grew more (as measured by NWEA/MAP scores) in that semester than in the previous 1.5 years combined. And she got about a quarter of the way through a standard Algebra I course.

Finally, I'd say this--about flipped classroom stuff generally and KA in particular. Right now, I'm cooking up a pot of Cincinnati Chili (mmm...can you smell it?). It's delicious, nutritious (yay low-fat turkey!), and my kids love it. But there's a diner down the street from my house, and any day I want, I can go there and get a reasonably tasty, reasonably healthy meal at a reasonably low price. And so every week or two--when I'm too tired, or we have nothing in the refrigerator--we go there for dinner. It's not Tru, or Topolobampo, or any of the other great restaurants Chicago is known for--but it's a reasonable way to get fed once in a while. I think KA and other online videos are like that: not as good as the best (although maybe if you watch the first lecture of the Udacity physics series, on Eratosthenes' measure of the circumference of the earth, you'd be surprised). But KA delivers reasonably clear, correct instruction to people who might not otherwise have access to it. Friends who have expressed skepticism about the "All Khan, All the Time" approach: I agree wholeheartedly. Let's give our kids a balanced diet of different kinds of instruction and different ways of thinking about problems. But I don't think that's a reason to trash on Khan altogether.