I suppose (well, hope) that the point of these statements is that their curriculum differs in some aspects. Maths (like all topics in school) is too wide to tea

I suppose (well, hope) that the point of these statements is that their curriculum differs in some aspects. Maths (like all topics in school) is too wide to teach everything, so they had to pick their battles. The 30% that aren't covered in the mass market books have to be provided by the teachers as additional material, while 30% of the books are not used in school. For $65, I'd expect more, too. On the upside: Assuming that the additional material isn't provided centrally, these teachers who wrote the book have more exposure to writing course work than their colleagues in Texas, who get optimized books.