Maybe one element of the metaphor that bears underlining is that Teflon has been used since the 1940s. It isn’t just the new that’s the problem. And you’re right, we do need to interrogate everything.

I do think about it from the perspective of the textbook writers, especially, regardless of their perspective on old/new school. They know there’s a problem, because they tried to script the lessons to make sure teachers don’t “mess them up.” But that’s worse than anything. In a way, it’s a design problem: even if you believe in the content, how can you make sure that translates into different environments, and remains robust? And that requires you to have content that won’t fail catastrophically if some portion of it is lost in translation.

For those of us with direct negative experiences with “old school” math education (personal and/or professional), passive acceptance based on tradition isn’t going to cut it. It’s imperative for us to try to break open the limited repertoires of traditional math teachers.

I suggest that a healthy approach to the Teflon problem is to reasonably interrogate EVERY lesson and ALL content on a regular basis. Maybe not everything every time every year, but surely some reasonable fraction (1/5?) every year, and then with everything revisited on a rolling basis at the end of the school year (perhaps during professional development in which the 1/5th is reviewed as a whole and the next 1/5th is briefly examined in anticipation of the coming year.

And whether a given lesson or group of lessons is traditional or innovative, it will be scrutinized the way you want Teflon examined for potential pitfalls, harm, etc. Without a willingness to put every lesson under scrutiny while worrying primarily about lurking disaster in anything and everything new, we’re likely to continue to be stuck in the same ruts that have held kids back for more than a century. I’d rather that we risk some scratched-up Teflon than guarantee little or no change.