Here's a tip: Change Time! Before you go to school, change the time. If it's still sleeping, good. First, go to the time screen, press the A+C buttons. Fix the date so it's the day before(Ex-it's February 8th today, change it to the 7th), then fix the time to 11:00, or just after your tama's bedtime is(Ex-it goes to sleep at 9:00PM, so set it to 9:01PM). Considering how long school is, by the time you get back, it'll be the 8th, and it'll still be sleeping, PLUS it still gains age at the SAME time! That's what I do every morning to my two tamagotchis, and it only takes about 1 minute!