One dad said his 11-year-old son was carrying up to 40 pounds of books home every day.

Now schools are saying that heavy backpacks have become a health risk.

"We had kids with health concerns with their backs because they were carrying so much," said Hoopes.

Schools are now taking action. In many schools, once kids arrive, their backpacks have to remain in their lockers. Other schools have purchased extra textbooks so that kids can leave their books at home. Still other schools have hired chiropractors, or doctors who fix backs.