The numbers can't be ignored: Roughly a third of children in the United States are now overweight or obese. In response, a growing number of schools are rolling out initiatives aimed at reversing the trend. Some have begun including children's body mass indexes on report cards; others are holding classroom fitness challenges. The downside of such programs is that they can cause kids of all sizes to feel judged, says child development expert Michele Borba, Ed.D., author of The Big Book of Parenting Solutions (Jossey-Bass). Take a tactful approach with these encouraging openers.