> If that's the case, then tetration is the right answer.

Sure, and whenever you're in a position to give that answer you should. But from the point of view of the girl her answer was right and 'better' than 999, and to deny her that small victory (especially with her being such a good student) would seem to me to achieve the exact opposite of what school is all about: to teach, to motivate and to reward original thinking, especially when it leads to better answers than the commonly visible ones. To dis-incentivize (I hope that's spelled correctly) that is the worst thing you could do to an otherwise motivated student.

If one wants to give an award for clever typographical thinking, then of course the teacher should consider an external discretionary reward.

If one wants to bring a lawyer to school to argue from a place of typographic visual logic, please be correct. The Common Core is right to question for the largest number possible with three digits. The Common Core implementation could say, "without operators", but then you'd have to explain what operators are and then not touch upon it again, and that becomes disconnected trivia. Otherwise, "without operators" is just there to stop another incident with a lawyer.

Self-efficacy is indeed important to a student's math success and interest. I don't think that correctly correcting a student will lead to unrealistic self-efficacy. I was being charitable by entertaining the logic of visual implicitness, which has little to do with math.

And one's self efficacy is a function of more than whether a teacher gives you an almost perfect score, if not for the accurately graded 3 digit problem. It's built by countless complex environmental feedback.

You're stuck in a groove. The whole thing could have been avoided, that is the point. But once people start digging in over something that should have just received a pass (note that it was you, not them that brought up tetration, which - unlike exponentiation - probably does not figure into their worldview of math to begin with) then you can expect all kinds of further confrontations.

The school messed up, pure and simple, everything else was just part of the avalanche that followed.

Feel free to try to out-do the world on the pedantry scale but you're not being productive and you are willfully missing the point.

You're being quite uncharitable to me by accusing me of foul or insincere behavior, though I've suggested nothing of that from you, and have responded robustly to your points. At the very least you could assume that we've failed to understand each other, but you instead assume a "willful" dishonesty.

I discussed self-efficacy. I discussed discretionary awards for creativity. I also discussed the problem from the young girl and her father's frame of discussion -- the frame of typography. You've not reciprocated with robust response. The pedantry is a point I'm making -- it's pedantry conforming to the pedantic frame they brought up. Tetration is no more the right answer than exponentiation. 999 is the right answer. The Common Core is good here.

If you're talking about how the school can skillfully avoid lawyers, then yes, that's the one point I've missed. The school can have all sorts of strategies to skillfully avoid lawyers. If that's the case, for anything which might summon a lawyer, do a cost-benefit analysis and form a school risk-averse policy. Is that the point you wanted to make?

If anyone brings a lawyer in to school, admit fault right away, and then go on teaching the same way, because 99.99% of children are going through the lesson just fine. Blogpost and HN moment successfully averted.

That was the only point I was making.

Whether tetration or exponentiation are the better answer, whether or not the dad should have stood by his daughter or not, none of that matters because it should have never even left the classroom in the first place, and they had multiple good reasons for doing that and none to dig in the way they did.

Once it did leave the classroom all bets were off.