Happy 50th birthday, Sesame Street. One of the most beloved American television series has changed a lot since premiering on November 9, 1969, but in fantastic news, one thing hasn't: its core mission of teaching children and instilling in them a love of learning.

Even today, Sesame Street remains the leader in this department. In a modern world of Paw Patrol and Calliou, TV series aimed at the toddler-and-preschool set can feel less educational and more like reasons for parents to light their hair on fire. Shows like Doc McStuffins and Wallykazam! bring targeted lessons, but not to nearly as diverse an age group, and their singular focuses mean one is either focusing on literacy or science, not both.

There was nothing on television like Sesame Street when it premiered 50 years ago, and the truth is, there’s still nothing quite like it now. (That's a big reason why it was such a valuable acquisition for HBO in 2015.) Throughout the years, the show has always been on the front lines of what’s important to teach children. And as some of the show's greatest hits demonstrate, long before educational advocates began popularizing the STEM acronym (Science, Technology, Engineering, and Math), Sesame Street was already there with silly characters promoting serious lessons.

The Yip-Yips

The “Yip-Yips,” a pair of blue and pink Martian explorers, were two of Sesame Street’s early characters. In their quest to figure out how things work, they would interact with different pieces of technology. Starting in 1971, they turned up to interact with devices children would need to learn how to use: telephones, clocks, radios, etc.

As technology moved on, the Yip-Yips began interacting with other devices, such as computers. In the year 2000, Sesame Street aired entire episodes focused on getting children comfortable with home PCs, and the Yip-Yips were there to help. As two of Sesame Street’s most memorable muppets (start yipping at someone between the ages of 25-50, they’ll hopefully know the reference immediately), that was only right.

Pinball Number Count

Before you can add, you must count. The Count has been preaching this gospel for five decades, but the most effective counting short the series ever did was this one. This animated segment had 12 versions, celebrating the numbers one through 12. With a funky earworm sung by The Pointer Sisters, it was the kind of thing that a kid could easily remember long after the TV turned off, later singing to themselves even if they hadn’t put the song’s words and the concept of counting together quite yet. It’s so memorable, modern pop music references it, such as the riff line on Janelle Monae’s “Many Moons.”

Monsterpiece Theater

Around the same time as the Pinball segments, Sesame Street introduced “Monsterpiece Theater,” a spoof of the neighboring program Masterpiece Theater on PBS, which gained household name status back in the 1970s with the Emmy winning Upstairs Downstairs. The earliest clips were straight parodies of whatever was airing (“Me Claudius”) or classic films (“The 39 Stairs”). But these soon became shorts about math, a slightly surprising turn considering the host was not the Count, but “Alistair Cookie.”

He introduced such fare as “1 Flew Over The Cuckoo’s Nest,” “Hill Street Twos,” “Lethal Weapon 3” (complete with that film series' stars), and “Gone With The Wind” (subtraction). Fans today know and love Sesame Street for recent parodies of prestige TV such as “Game of Chairs,” “Sharing Things,” or the ever-popular “Star S’mores,” all of which have millions of views on the official YouTube channel. “Monsterpiece Theater” is where the show got its start doing such work.

“Put Down The Duckie”

How does one teach holistic concepts like cause and effect problem-solving and “if this, then that”? It's a hard concept for small kids to grasp, but the sooner they do, the easier it is to understand basic programming. It’s the part of STEM that doesn’t get mentioned in the acronym, but it’s probably one of the most important connections for kids to make.

It’s a difficult idea to teach in a three- to four-minute TV segment. Sesame Street not only figured it out, but the series did it with one of the show’s most memorable songs of the 1980s: the big-band Hoots The Owl-led song “Put Down The Duckie.” The chorus—“You gotta put down the duckie if you wanna play the saxophone”—isn’t just fun to sing, it’s an entire philosophy on reason that applies to many of life’s problems. It wound up being so popular that the show did a second, celebrity-heavy version for the 1988 “Sesame Street Special.” (Best part: the song still slaps all these years later.)

Prairie Dawn, Scientist

In the 1990s, Sesame Street became more conscious of inherent biases built into the original program, particularly its lack of leading female muppets. In response, it added the “Around the Corner” set, introduced muppets like Zoe and Natasha, and produced segments where female muppets hosted explicitly STEM-angled concepts. For the latter, they brought in long-running character Prairie Dawn to host segments that were first called “The Little Blonde Scientist Show.” Thankfully, they were rechristened “Prairie Dawn, Scientist” in subsequent sketches.

Like many of the '90s and early '00s additions, these didn’t necessarily bring a new spark to the show. Instead, they fit in perfectly with what was already there, just with a female muppet as the central figure (one who had been with the program since the beginning, in fact). No fanfare, no fuss. It’s just another funny segment, and it doesn't make a big deal about the casual inclusion, so children watching wouldn’t think it remarkable, either.