The sad thing is that math that any grade or secondary school kid will learn hasn't changed since Newton and Leibniz, and even then, only the most advanced students learn calculus in school. What has changed is technology, and I think that books should reflect to some extent the new problem solving methods (graphing calculators and the like). But for the most part, a math book from the 1920s, if its binding were still good, should be good enough. All a book needs is practice problems (the advent of extensive example problems and solutions, absent from very old editions is nice development, I suppose). The teacher should be doing the teaching as (s)he sees fit. Nouveau math teaching methods are a scam. 2 + 2 will always equal 4. If it doesn't, you better be in philosophy class, not math. There is no way to learn math other than practice. Period. End of story. Some students can learn with less practice and some need more, but no one understands long division innately or is born knowing the times tables. I think some of this travesty can be linked to the meteoric rise in the number of graduate degrees in education that are handed out these days. One can't write a thesis without a new topic, so new methods need to be continually invented, evaluated and reinvented as a university exercise.