Early one morning this week, our daughter, Rachel, was preparing to catch the school bus. We chatted as she searched for her shoes and scrounged in the refrigerator for an orange. She casually mentioned that her backpack was awfully heavy.

I reached to pick it up with one hand. I couldn't. I centered myself and lifted it with both hands. It felt like it was stuffed with paving stones. Oblivious to the impending arrival of the bus, I marched Rachel and her backpack into the bathroom.

All those years of studying percentages in math class had been preparing me for just this moment. I first weighed Rachel (127 pounds) and then had her step on the scales holding the backpack (151 pounds.) That meant she was toting 24 pounds of books and supplies most of the day — almost 19 percent of her body weight.

First I thought perhaps she was carrying a lot of superfluous materials, but that wasn't the case. The only items in the pack were books, notebooks, a calculator and a pencil box.

My concern just elicited one of those "please, mom, it's not a big deal" smiles from Rachel. She hoisted the backpack over one shoulder and stumbled out to meet the bus.

I started doing some online research. My initial query dealt with the recommended maximum weight a child should attempt to carry. Turns out occupational therapists recommend that a student's backpack weigh no more than 15 percent of their body weight. Already Rachel was in the danger zone.

Then I discovered I was doing my research on National School Backpack Awareness Day.

For the last 10 years, the American Occupational Therapy Association has designated the third Wednesday in September as a day to highlight the ergonomically correct way to use backpacks or, as they phrase it, "Pack it light and wear it right."

This is a significant public health issue. Each year, more than 5,000 school children go to emergency rooms because of injuries related to over-weighted backpacks. In a recent study, 60 percent of school-age children reported chronic back pain related to heavy backpacks.

The AOTA has published 10 tips to avoid backpack-related health problems:

n Never let a child carry more than 15 percent of his or her body weight. This means a child who weighs 100 pounds shouldn't wear a backpack heavier than 15 pounds.

n Load heaviest items closest to the child's back and arrange books and materials to prevent them from sliding.

n Always wear both shoulder straps. Wearing only one strap can cause a child to lean to one side, curving the spine and causing pain or discomfort.

n Select a pack with well-padded shoulder straps. Too much pressure on shoulders and necks can cause pain and tingling.

n Adjust the shoulder straps so that the pack fits snugly to the child's back. The bottom of the pack should rest in the curve of the lower back, never more than four inches below the child's waistline.

n Use the waist belt, if the backpack has one, to help distribute the pack's weight more evenly.

n Check what your child carries to school and brings home to make sure the items are necessary to the day's activities.

n If the backpack is too heavy, consider using a book bag on wheels if your child's school allows it.

n Choose the right size pack for your child's back as well as one with enough room for necessary school items.

n If a student is experiencing back pain or neck soreness, consult your physician or occupational therapist.

That evening I had Rachel put on her backpack. Sure enough, she was wearing it too low on her back. A few adjustments and it was much more comfortable. I also warned her against carrying it shoulder-bag style. That's just looking for trouble.

There's nothing we can do about the weight of the backpack. With this year's change from a four-period school day to a seven-period one, there are almost twice as many textbooks to haul around. In a building the size of North Hall High, there's no time to run back and forth to a locker in between classes.

Rachel may not be able to pack it light but at least now she'll wear it right.

Teressa Glazer is a Gainesville businesswoman. Her column appears biweekly on Fridays and on gainesvilletimes.com.