Jenn Jarmula, an elementary- and middle-school teacher in Chicago, recently hung a sign outside her classroom. This Is A Fidget Spinner Free Zone, it read. Fidget spinners–which dominate Amazon’s ...

You’ll find them in nearly any department store or gas station: Fidget spinners, fidget cubes, and other devices designed to help you focus. There’s no scientific evidence about whether they work, but ...