If you’re a parent or a teacher, you probably say “wash your hands” more than any other phrase. Chances are, the kids in your life just don’t understand why hand-washing is such a big deal. Well, here ...

Mold has all the hallmarks of a cute microorganism: it’s small, colorful, and fuzzy. But when you open your bag of sandwich bread to find that small splotches of the stuff have preemptively colonized ...