Gretchen is the smartest of the main kids in the show. In a few episodes, it's shown that she's smarter than almost everyone else in town, as shown in "A Genius Among Us", where it's established that she's smarter than most of the teachers at school. Gretchen is also somewhat of a "big sister" to the main six, usually to T.J. and Gus. She often argues with Vince but appears to be very close to him as well, hinting that she may have feelings for him (and vice versa). Out of all the members of the main six, Gretchen seems closer to Spinelli than she does to any of the boys.
Although she is very smart, she can also be sweet, and a bit naïve (mostly due to her young age). At times, she can easily fall for most of the crazy stories told on the playground, such as the outcomes of the Stinky Peterson fortune teller in "Gus' Fortune". She's also very unathletic, as shown in "Gretchen and the Secret of Yo," but is shown to be very skilled at yo-yos.
She is one of the few kids on the playground to get along with one of the Ashleys, Ashley A., as seen in "Outcast Ashley", where Ashley A. is kicked out of the clique for forgetting a tradition in the group. When looking for friends, she decides to hang out with Gretchen. The two become friends for a while until Ashley A. is welcomed back into the clique. Their friendship is seldom seen again.
One device Gretchen is usually seen with is her Galileo, a small, handheld computer with a talking frog mascot.
Recess: School’s Out
After their last day of school, T.J. is looking forward to a fun-filled summer with his friends, right up until they tell him that they are each going to summer camp, with Gretchen going to space camp. T.J., disconsolate, accompanies his friends to see them off.
Two days later, T.J. summons them back when he notices suspicious activity going on at the school, and witnesses Principal Prickly get dematerialized. Sneaking a box of documents from the school and finding it only contains useless school stuff, Gretchen and the others get the impression that T.J. made the whole thing up just to get them back, especially when they see a person resembling Principal Prickly leaving the school. Just as they are about to go back to their camps, they witness a tractor beam rise from the school roof and shoot a green laser beam, making them realize that T.J. wasn’t lying.
T.J. then comes up with a plan so that his friends’ absence from their camps will be kept secret: they’ll go back to their camps during the day and meet up again in the evening. Gretchen provides her special digital camera to monitor the school at night. The next evening, after T.J. acquires Principal Prickly’s discarded golf pants from the school dumpster while hiding from Kojak and two other guards, Gretchen concludes that the pants are indeed Prickly’s, and she also finds a note that reads “Help Me!” in the pocket, confirming that Principal Prickly is being held prisoner in the school.
The gang infiltrates the school to rescue Prickly. While there, they observe the same device from the day before being shot at the moon, and get caught after Mikey belches from the air vent, and end up tumbling out after their combined weight causes the vent to collapse. The ringleader of the operation, Phillium Benedict, orders his guards to capture the gang. T.J. is captured and locked up in a storage room where he finds Principal Prickly, while the others narrowly escape, running past Ms. Finster and Randall, causing them both to suspect that something is amiss at the school.
Going to the police station, the kids tell the officers about what’s happening at the school, only to get laughed at. They look through the box of documents that they took from the school again, to which Spinelli acquires a date book that speaks of Lunar Perigee, which she mistakes for an Italian girl, before Gretchen explains to them what it means. She also mentions seeing strange abnormalities in the moon’s position while at Space Camp, then concludes the machine they saw in the school auditorium is a tractor beam, adding that if a tractor beam were aimed at the moon at Lunar Perigee (12:22 pm the next day), it could alter the moon’s orbit.
Moments later, T.J. acquires his confiscated Walkie-Talkie from Principal Prickly’s office, where they discover Benedict’s true plan to get rid of summer vacation, and alert the gang before Kojak takes the walkie-talkie from T.J.. Knowing they can’t stop Benedict on their own, they inform Becky about the situation and persuade her to drive them to their camps and rally the other students.
After gathering up all the students, Gretchen futilely tries to get their attention, but they think it’s pointless. Luckily, Gus steps in to take charge of the student body and concocts a well-thought-out plan. Mikey distracts the guards by singing, causing them to try and get rid of him, only to fall into a hole that the Diggers dug up. Gus, Spinelli, Gretchen, Vince, and the Ashleys sneak past the guards while they are distracted. Spinelli, Vince, and Gus subdue the guards by luring them towards their units. Gretchen, meanwhile, goes to the electrical room and turns off the power to the auditorium, then locks Fenwick and two scientists in the room when Benedict orders them to fix it.
Reuniting with T.J. and Principal Prickly after they defend them from Kojak, the group reaches the auditorium to confront Benedict. However, he brings in more guards to keep them from trying to stop him. Just before he has a chance to activate the tractor beam, Ms. Finster bursts in, accompanied by the other teachers. In the ensuing fight, Gretchen resorts to spraying gooey string at the scientists with help from Becky. The battle ends with Vince destroying the tractor beam with T.J.’s baseball, and Benedict and his goons getting arrested.
T.J.’s friends approach him to say that they have plenty of time to get ready for their futures, and they still have three months of summer. After speaking with Principal Prickly to say thanks, T.J. and his friends go off to the pond.
- She, Gus and Mikey are the half of the main six to be only children—T.J. has an older sister, Vince has an older brother, and Spinelli has two older brothers.
- Her parents appear to be geniuses as well, so it's implied that her brains come from them.
- In the original pilot from 1996 (which would be re-made into the first episode), she had a slightly different appearance, such as her being given black hair, slightly larger buckteeth, and the blue part of her dress was white with green dots.
- Ten years after she debuted, another Gretchen, from Phineas and Ferb, was introduced, having very similar features to her.