... For decades, efforts to improve math skills have driven schools to embrace one math program after another, abandoning a program when it does not work and moving on to something purportedly better. In the 1960s there was the “new math,” whose focus on abstract theories spurred a back-to-basics movement, emphasizing rote learning and drills. After that came “reform math,” whose focus on problem solving and conceptual understanding has been derided by critics as the “new new math.” Singapore math may well be a fad, too, but supporters say it seems to address one of the difficulties in teaching math:...