Pencils and erasers aren't the only thing students bring to school this season; 85 percent of all school districts report at least one outbreak of head lice every year, according to the Centers for Disease Control and Prevention. The majority of the 12 million annual head lice cases occur in preschool and elementary school children, due to their generally closer contact with each other than older students.

The most common way for lice to transfer is through head-to-head contact. Lice do not fly or jump; they only crawl, and they move slowly enough that it can take 30 seconds or more to move from one head to another.

Lice can survive off a human head for 24-36 hours and can therefore be transmitted through contact with pillows, hats, hair brushes, athletic helmets and other personal items. They are more common in girls than boys, probably because they tend to share more personal items.

The color of lice changes throughout the life-cycle.  Eggs are nearly colorless, hatched eggs (called nits) are light yellow or whitish gray, and adult lice are grayish brown in color. Nits are smaller than a pin head and extremely hard to remove. They thrive on the scalp and in "hot spots" such as part lines, the back of the neck and behind the ears.

Swimming carries no greater risk of transmission, but it doesn't kill lice, either; they go into a state of suspended animation when in water and remain firmly attached to the hair shaft.

It's easy to mistake dandruff, food or hair products for eggs or nits. One way to know the difference: If the particle can be removed easily with your fingers, it's not a nit. 

Symptoms of head lice include itching at the scalp, small red bumps or sores on the neck or scalp, and a tickling feeling of something moving in the hair. Here are some tips on how you can reduce the chances of your child bringing home more than homework with them:

• Warn your children to never share hats, combs, pillows or helmets

• Keep long hair in a braid or pony tail to help minimize contact with infected surfaces.

• Don't wash your child's hair every day; lice attach themselves more easily to squeaky clean hair.  Wash every other day so natural oils will build up and make it harder for lice to latch on.

• Use hair care products designed to repel lice without harsh chemicals or pesticides. Herbs such as rosemary, citronella and tea tree have been proven to repel head lice; the smell keeps them away.

• Do weekly head checks under a bright light. Comb through tiny sections of the hair and check "hot spots" such as the back of the neck, part lines and behind the ears.  (If a gray or white fleck is hard to remove, it's a nit and not dandruff.)