First-class fliers have a code. It’s subtle and usually comes with a glass of champagne. If you want fit in before you fall flat in a sea of stares, learn the unspoken rules—lest you mistake the amuse ...

One of my first vivid memories of math is of timed tests. I still remember how visceral my panic felt–sweaty palms, heart pounding–as I scrambled to recall facts before the clock ran out. You might ...