I read the transcript. Just now I went back and read the paragraphs to see if I was missing relevant information, but I wasn't.
You can't tell me that's not an effective lesson he's put together.
Well, you've hamstrung me before we begin, but I'll roll with the spirit and tell you what would happen if the teacher executed this brilliant lesson plan in almost any math class I ever took. And I went to nationally-recognized schools.
25 kids in the class, call 'em 10 year olds.
Around eight of them are so far ahead of their peers that they essentially haven't learned a single new thing in actual math class since first grade and therefore aren't paying attention (or if they are, "What column is that?" the hundreds column, you stupid fuck. get me out of here)... if the teacher is lucky they're shy types, if not, the lesson is likely to end before it begins. I was an extremely clever bored kid and when the mood struck me (read: the teacher recklessly confiscated my copy of Lord of the Rings) in elementary school the class simply couldn't begin until I had been absented to the principal. Fuck 'em, even after all these years...
Moving on, maybe 10 more are bad at math and know it (and yes, faux-inclusive education movement aside, it is absolutely possible to be 'bad at math' no matter how hard you try -- though note this can be different from being able to do most math). Therefore they don't really want to answer questions, even seemingly easy ones. They know there's a trick somewhere, or the questions wouldn't be asked; they know they suck at math; they know they aren't saying a word until called on explicitly. They've been burned before. Probably some of them are asleep because their rich parents have long since bought them tutors: the tutors will report to mom if they sleep at tutoring, but the overworked teacher (probably) won't notice, so.... Without realizing it they've taught themselves rudimentary logic, but that's an irony for a different post.
The next group, six kids, the ones whose existence means no sane public school teacher will ever try this exercise. The teacher asks how many ways you can write zero, and they shout back answers like 'fart'. The whole day is wasted sorting things out.
And finally, if all other obstacles have been miraculously surmounted, every class has a Hermione or two. That's the true issue with teaching by the Socratic method in a classroom environment: one overzealous and under-socialized kid will answer every single question before anyone else has even bothered to think about them. And once that happens, you lose any of the middle 10 who may know some of the answers (or may be capable of reasoning to them, slowly), but are too worried about being dumber than Hermione to shout them out. You also provide a focus for the latent envious cruelty (the sort only children ever truly use) of the group of six, and the out-of-class bullying worsens.
End result? Class destroyed, Hermione crying or dead, smart kids even more jaded (cough), teacher still making $13/hr after taxes and retirement contribution.
I don't know what schools you went to, where, or when, or your kids either, but look me in the eye and tell me my scenario isn't more realistic than the author's. His is, at best, a lucky edge case; mine is the drudgy reality in the majority of public schools.
And with my tongue out of my cheek (mostly...), what I meant by my first comment is that the Socratic method is wonderful for convincing someone in a one-on-one environment to change their point of view on a subject, because people do not change their mindsets from without. (You'll note that this is how it was applied... by Socrates.)
But it was not meant for a group setting. It might work if every member of the group was for some reason deeply invested in the process of finding truth, but that just don't happen in fifth-grade math.
Which is why I have ever preferred the lecture. If a student wants to pay attention, they will; if not, they don't have to! But I'm not a teacher and could never be. My claim to expertise is only that I went to an American public school.