Hair is a built-in security blanket, silky and comforting to the touch. For some twirlers, the habit may have a calming effect that helps them focus.
The substitute: If your child likes to helicopter her hair wildly in math class, supply her with a stash of rubber bands or string, which can be wound around the fingers (or dreamily tied in knots). Or let her play with a beaded necklace.
Also try: To reduce temptation until she kicks the habit, pull her hair back into a ponytail or even crop it into a sporty short cut.
More drastic measures: In a small percentage of cases, twirling can develop into trichotillomania, a rare condition in which a person pulls her hair out. If you notice bald spots or if your child seems to pluck hair obsessively rather than absentmindedly, consult your pediatrician.