"Sesame Street" began as a way to help disadvantaged preschoolers learn their numbers and alphabet so they could start school on par with their more advantaged peers.

The idea of using TV to teach was controversial, of course.

After all, children's programming had been "edu-taining" for years - with limited academic results.

But "Sesame Street" was different. It was designed to attract parents and kids. The idea was that they would watch it together, and moms and dads could continue the lessons.

Rebecca Jensen's children have grown up on "Sesame Street." Her oldest are 19 and 13. Her youngest, Leo, is 3 and watches it religiously.

"I love 'Sesame Street,'"

the Belmont Elementary School kindergarten teacher said. "I think it is most educational show out there."

"Sesame Street" has "stickiness," says author Malcolm Gladwell in his book, "The Tipping Point." The show not only caught children's attention but had a far-reaching influence on their school readiness and ability to learn.

It changed its format to best meet preschoolers' needs, he writes, noting how in 1969 developmental psychologists told producers they should not mix fantasy characters (Muppets) with real people because it would confuse children. But preschoolers lost interest when only human characters were on the screen. So "Sesame Street" had humans and Muppets engaged in conversation and working together to solve problems.

Since its debut 40 years ago, "Sesame Street" has been the subject of more than 1,000 educational studies, all of which have found "Sesame Street" teaches preschoolers and helps them learn later. Children who watched frequently scored better on achievement and school readiness tests, and made more cognitive gains compared to children who watched infrequently, a study by the Educational Testing Service found.

Other studies found these children had broader vocabularies, better letter and number recognition and could identify printed words more easily than their counterparts. They also learned to cooperate better.

"Sesame Street's" educational focus has always included social, emotional and cultural issues. From the start, "Sesame Street" was racially diverse. As early as 1971, kids were introduced to Spanish through Maria and Luis, who owned the Fix-It Shop. In 1991, the Muppet Rosita joined the cast, frequently mixing Spanish words into English sentences. By 2002, Spanish Word of the Day became a regular segment.

Over the decades, the Muppets and humans have gently and thoughtfully addressed real topics: adoption, single parents, death, HIV, disabilities, bullies, natural disasters, fear, the impact of war and healthy living.

The format is similar for international versions. Mexico's show concentrates on literacy, diversity and gender equity. In Kuwait, cultural traditions, legends and history are the focus. In France, the emphasis is poetry, art and music.

And as the show goes on, so do the culturally relevant topics.

The 40th season will debut "The World is Green and Growing," to promote environmental respect and awareness. First Lady Michelle Obama will help Elmo plant a vegetable garden.

But just how sticky "Sesame Street" remains in the competitive multimedia world remains to be seen.

On Friday, for show and tell, one of Jensen's kindergartners brought in Big Bird. Few of her students knew who he was. Some thought he was a chicken; others guessed a duck.

Maybe "Sesame Street" is losing its appeal.

"Which makes me so sad," Jensen said. "It was so huge when I was growing up. It's an awesome show."

Reach Erin Andersen at 473-7217 and eandersen@journalstar.com.