We recently wrote about how infinitely large sets are not all the same size as each other, but we were a bit vague about what we meant by a set. The people who invented set theory also started out ...

Every Saturday morning at 10 a.m., Jason Zimba begins a math tutoring session for his two young daughters with the same ritual. Claire, 4, draws on a worksheet while Abigail, 7, pulls addition ...

What do you get when you add up more than a billion dollars, plus a foundational but often overshadowed K-12 subject, and multiply it by the influence of the biggest player in K-12 education ...