You don't get to be the longest-running children's show in TV history by doing the same thing over and over. So even though parents who grew up watching Sesame Street can still see old favourites like Big Bird, things on the street have changed since the show debuted 45 years ago on Nov. 10, 1969.

Cookie Monster now exercises self-control and sometimes eats fruits and vegetables. Millions of kids watch the show on phones and computers instead of TV. And there's less time spent on the street with human characters. They're just not energetic enough for today's viewers.

'We design the show to engage the parent because we know that's more educational. If you have a parent watching with you, you're going to learn much more' - Sesame Street senior vice president, Scott Chambers, on engaging families watching

That Sesame Street still exists at all says a lot. In 1973, it was one of two TV shows for preschoolers. Now it's competing with 84 kids' shows on TV and countless others online. Yet Sesame Street still holds its own, ranking 20th among kids ages 2 to 5 with 850,000 viewers per TV episode, according to Sesame Workshop, the nonprofit organization behind the show.

New digital dimension

But now half the viewers watch it in digital formats. Options include SesameStreet.org, PBSKids.org, Netflix, Amazon, iTunes and some 50 apps. A Sesame Street YouTube channel has a million subscribers and 1.5 billion views. And touchscreens have been "a magic wand for us in terms of engagement," says Sesame Street senior vice president Scott Chambers. Kids can trace letters or point to colours or shapes, and the app provides positive reinforcement.

  • On mobile? Watch Johnny Cash performing on Sesame Street in 1973 here
Sesame Street

Sesame Street hosts Matt Robinson (Gordon), Will Lee (Mr. Hooper) Loretta Long (Susan) and Bob McGrath (Bob) stand with Big Bird on the set in 1969. (Children's Television Workshop/Getty Images)

Sesame Street also has the highest "co-viewing" experience — meaning adults watching with kids — of any preschool show: 49 percent of "Sesame Street" viewers are over age 18. "We're very proud of that," said Chambers. "We design the show to engage the parent because we know that's more educational. If you have a parent watching with you, you're going to learn much more."

That's why sketches often have contemporary celebrity guests or pop culture references that 2-year-olds don't get, but adults do. A James Bond parody stars Cookie Monster as a secret agent, Double-Stuffed 7, in The Spy Who Loved Cookies. Another show celebrates "what makes people special," with Elmo telling Lupita Nyong'o that her skin "is a beautiful brown colour." The actress responds, "Skin comes in lots of beautiful shades and colours ... I love my skin!" It's a classic Sesame Street lesson about diversity that goes back to its groundbreaking roots as one of the few shows in the 1970s to feature all races and ethnicities. Today the show also routinely features children with disabilities.

  • On mobile? Watch  Lupita Nyong'o's Sesame Street appearance here

Older episodes come with warnings

Parents whose kids watch old episodes may be puzzled by warnings that the material may be inappropriate for today's children. But remember "Monsterpiece Theater," a parody of PBS' Masterpiece Theater? Back in the day, Cookie Monster hosted the show as Alistair Cookie, and he had a pipe, imitating the real show's human host Alistair Cooke. Cookie Monster gobbled the pipe up rather than smoking it, but any reference to smoking is now unacceptable.

  • On mobile? Watch a clip of Monsterpiece Theatre here

The music has changed too. Those memorable lyrics, "Sunny day, sweepin' the clouds away, on my way to where the air is sweet," still open every episode, but now the song has a syncopated, jazzier beat. Other sketches feature hip-hop or Latin music. In one new episode, rocker Elvis Costello pops up singing, "A monster went and ate my red two" to the tune of his famous line, "Angels wanna wear my red shoes." The Dracula-like Count von Count puppet uses a disco beat to teach a lesson about the number nine in his "Number of the Day" segment, and every episode ends with "Elmo the Musical," with Broadway-style songs and a velvet curtain.

  • On mobile? Watch Elvis Costello sing with Elmo here

More muppets, less humans

Newer seasons also feature less of the actual street with human characters, and more puppets in skits with animation or other technical wizardry. Executive producer Carol-Lynn Parente says the puppets "have a madcap energy to them" that helps Sesame Street compete with the many other kids shows that are animated.

Sesame Street also is unique because before any scripts are written, child development experts offer input on what today's kids need to succeed in school. That's why in addition to teaching letters, numbers and values, the show now teaches behaviours like impulse control and listening to directions.

Cookie Monster

Sesame Street says Cookie Monster gives children some practical tools to help deal with impulsiveness. (SesameStreet.org)

"Cookie Monster has been our poster child for self-regulation because of his love of cookies," said Parente. The puppet sometimes now eats fruits and vegetables instead — although he may also devour the plate, table and chair.

Elmo also remains a central part of the show, despite a real-world scandal in which three men accused the puppeteer behind Elmo, Kevin Clash, of underage sexual abuse. Those lawsuits were dismissed in 2013 because the statute of limitations on the accusations had run out.

Not all of today's parents love Sesame Street. Some say it simply doesn't keep their kids' attention. Daphne Mallory, a mother of four in Twin Falls, Idaho, grew up watching Sesame Street but says her four children don't. "It lost its relevance," she said. "It's geared toward engaging the parents watching the program with their children, rather than truly educating the children. While I appreciate celebrity appearances, I find it distracting more than adding to the experience."

But Lori Chajet of Brooklyn, New York, says her daughters, now 7 and 10, loved it — including old episodes they got on tape — while she and her husband appreciated the emphasis on multiculturalism and the pop culture references for adults.

"Little kids learn from it," said her 7-year-old daughter Sasha, "but they really have a really fun time watching it."