Developmentally, preschoolers love anything with singing, repetition, and colorful characters. That's why they love shows like Sesame Street. But they'll absorb anything -- which means they can learn their ABCs or meaningful lessons on how to get along with others, or they can learn about junk food.

Try this: Preschoolers can't tell the difference between an ad and a program. Instead of learning about a sugar cereal, let your kids watch children's shows without commercials where they can build reading readiness skills. It's healthier. And limit TV time. Doctors recommend under 30 minutes a day.