My 13-year-old son is much smaller than the other boys in his class. When I picked up his backpack the other day, it must have weighed close to 30 pounds. He only weighs 80 pounds. Isn’t his backpack too heavy for his size?

The usual guideline for maximum backpack weight is 10 to 15 percent of the child’s body weight. This would mean eight to 12 pounds for your son. Most students actually carry closer to 20 to 25 percent of their body weight. At 30 pounds, your child is at the upper end of this amount.

Researchers are studying the question of how much backpack weight is too much. Until a clear guideline is established, common sense must prevail. Help your child check his backpack each day and keep out unnecessary items.

Check with the school for guidelines, and don’t hesitate to weigh your child’s backpack. If the backpack continues to be more than 15 percent of his weight on a daily basis, talk to school staff about the number of books your child is carrying.