1. Fix their sleep schedule. A good trick is to set your kids' bedtime about 15 minutes earlier each night.
According to the American Academy of Pediatrics, kids between the ages of 6 and 12 should get 9 to 12 hours of sleep a night, while teenagers need 8 to 10.
2. Get a checkup. If your kids haven't had their annual physical or vaccinations yet, it's time to do that. It's also a good idea to make sure the school has any medications they need on hand . . . and that your emergency contact information is up-to-date.
3. Make them a healthy lunch. One trick to get them to actually eat it is by buying a bento-box-style lunch box that you can fill with small portions of healthier foods. And always remember to pack a drink, since a study in 2015 found that more than half of all children and teens aren't properly hydrated.
4. Go over hand-washing. Since you won't be supervising their hand-washing when they're at school, make sure they know how and when to wash their hands. According to one study, kids who wash their hands frequently are 38% less likely to have to stay home with a cold during the school year.