Math is, by definition, a subject about numbers. But at the National Council of Teachers of Mathematics this week, math educators said the subject has its own language, too—and knowing how to speak it ...

Picture a tune that plays with your mind. It does not go straight but skips and flips in ways you do not expect. That is math rock. It avoids common music paths, which makes it feel fresh and smart.

For children who find math difficult or frustrating, or who just like to be challenged, there are many cool math games online to play for free. But are they useful? Research shows that the brain’s ...