Don't worry, if it doesn't have it then I'm sure a future model of this watch will have a "I'm not on a wrist" logging/alerting function.

So the kids need to figure out that in order to do this kind of thing they need to attach their watch to some less-cool kid's wrist that stays at school while they do the fun things. At least that less-cool kid hopefully gets some kind of reimbursement for offering that service.