Sherri Cater doesn't look forward to report card time. It's not that the ticket operations manager at Mountain High, Calif., is worried about her grades. Rather, she knows that sullen teenagers will soon be walking up to the ticket counter asking why their passes suddenly don't work at Mountain High's automatic lift gates. The resort, located about 90 minutes from Los Angeles, uses credit card-like electronic lift tickets that contain computer chips. You can buy anything from a single lift ride to a full season pass and put it on a card. When you approach a lift, a scanner automatically reads your pass, flashes your photo on a screen in the lift maze and opens the control gates. "A lot of parents buy passes based on their kids maintaining a certain grade level," Carter explains. When report cards hit home, she starts getting calls from parents-usually mothers-who deactivate cards for offspring who aren't making the grade. "A teenager will walk up and say, 'My pass is broken.' And I'm like, 'Hey, I know that. Your mother shut it off. You better call home.'" The offenders tend to fall into three groups: "mostly boys, mostly young teens and almost always boarders."