Then explain why my daughter's 2nd mathbook teaches subtraction SIX different ways. Yep, lots of A/B testing there, lets just try every possible, confusing metaphor so the kid doesn't master anything.
Time is money, even in the classroom. If you spend time teaching x four different ways til Sunday, the kids have no time to master any singular technique.
The bigger question is why does teaching subtraction require a textbook at all? Surely if I asked anyone here to think of six ways to teach a child subtraction, none of the ideas would involve a textbook (or a worksheet).
I think they might. You might combine an activity with placing and removing physical things, then showing on paper how the symbols represent this, then having the child try some problems on their own. You could do all the written parts yourself, or you might use a text that had it done for you already. And then the student might practice in a workbook.
Wouldn't that make sense? I feel like bad textbooks have given the idea of text books a bad name. And I don't think this is a "no true Scotsman" fallacy. It's more an issue of mostly horrible Scotsman written to align with ridiculous state standards.
