Add Yahoo as a preferred source to see more of our stories on Google. Fifteen years after the calamitous rollout of the Common Core math standards, the once-derided strategy has proven its staying ...

In the long division problem used as an example under the heading “area model,” the right column showed 7 minus 0 equals 0. It should have read 7 minus 7 equals 0.

A correction to an earlier version of this article has been appended to the end of the article. When Veera Sinha was a little girl in India, her father asked his kids to solve math puzzles in their ...