"Sesame Street" officially turns 50 this weekend. That's 50 years of Bert and Ernie, 50 years of Oscar and Big Bird, and 50 years of expanding minds, stretching boundaries and occasionally stirring up controversy.

Why it matters: As was the original intent, "Sesame Street" has played a huge role in teaching generations of kids not only how to read and count, but also about the world around them.

"It was very important for us to represent a range of races and ethnicities, not only in our human cast but also in our puppet cast," Sesame Workshop senior VP Rosemarie Truglio said in an interview. "Keep in mind, 'Sesame Street' is a very diverse and inclusive neighborhood. We have monsters, we have grouches and we have an 8-foot bird."

Celebrity guests over the years — everyone from Ray Charles to Christopher Reeve — added more diversity to the Sesame regulars, all in service of helping young kids make sense of a complicated world.

"It's a mirror for them to see themselves, and it's a window for them to learn about others," Truglio said.

If you want to hear what Cookie Monster, Count von Count, Bert and Abby Cadabby think about this, be sure to watch the video.

Yes, but: During its five decades of trying to bring a diverse and complex world to preschoolers, Big Bird and his friends have also managed to step on a few toes.

Race: "Sesame Street" has been racially diverse since the outset, attracting criticism both from those who saw a liberal bias and from those who objected to its representation of minorities. An early Muppet character, Roosevelt Franklin, was beloved by many, including the show's black staff, but was ultimately sidelined for what some saw as a perpetuation of negative stereotypes.

"Sesame Street" has been racially diverse since the outset, attracting criticism both from those who saw a liberal bias and from those who objected to its representation of minorities. An early Muppet character, Roosevelt Franklin, was beloved by many, including the show's black staff, but was ultimately sidelined for what some saw as a perpetuation of negative stereotypes. Autism: While widely praised for introducing the concept of neurodiversity through Julia, an autistic muppet who debuted on the show in 2017 (and digitally back in 2015), "Sesame Street" drew criticism from some in the community because of its partnership with Autism Speaks, a powerful but polarizing nonprofit that encourages parents of a newly diagnosed child to grieve for their loss. The show's work with Autism Speaks led another group, Autistic Self Advocacy Network, to sever ties with it despite having previously partnered around Julia.

While widely praised for introducing the concept of neurodiversity through Julia, an autistic muppet who debuted on the show in 2017 (and digitally back in 2015), "Sesame Street" drew criticism from some in the community because of its partnership with Autism Speaks, a powerful but polarizing nonprofit that encourages parents of a newly diagnosed child to grieve for their loss. The show's work with Autism Speaks led another group, Autistic Self Advocacy Network, to sever ties with it despite having previously partnered around Julia. Move to HBO: One of the most controversial moves in recent years was the deal between Sesame Workshop and HBO. The arrangement helped ensure the organization's growth and financial stability, but also means new episodes air first on HBO and come later to PBS, which critics say is the opposite of the original intention, which was to first serve low-income kids.

Truglio acknowledges that "Sesame Street" hasn't always gotten things right. One early episode, for example, talked about divorce.

For kids that had been through that experience, it may have been great to see their experiences reflected.

But for a lot of other kids, it raised a new and scary possibility, sending them to ask their parents if they were getting a divorce.

"That's why we've got to be really careful on these sensitive topics when you bring it to a mass audience," Truglio says.

After 9/11, for example, rather than discuss the attack directly, the show had its characters confront something smaller in scale and closer to home — a grease fire in Hooper's store.

These days, "Sesame Street" has a separate website — Sesame Street in Communities — that deals with some of its toughest subjects, including addiction and homelessness.

What's next: In Season 50, "Sesame Street" will focus on life lessons, such as persistence and resilience. Next month, it will also reissue Joan Ganz Cooney's 1966 report "The Potential Uses of Television in Preschool Education," which led to "Sesame Street" noting that many of its findings remain prescient in the era of smartphones.

Editor’s note: Axios partners with HBO for "Axios on HBO."