Jan Berenstain, who created the popular children’s series “The Berenstain Bears” with her husband, Stan, died of a stroke Feb. 24, according to the Associated Press. She was 88.

Featuring Mama Bear, Papa Bear, Sister Bear and Brother Bear, the Berenstains’ books focused on teaching preschoolers about social situations, from making friends to going to summer camp.

Jan and Stan wrote and illustrated more than 300 titles together, from 1963 until Stan’s death in 2005. The series has sold more than 260 million books and has earned a cherished spot on young readers’ bookshelves.

In this January 2011 photo, Janice Berenstain displays copies of the first, left, and second books that she and husband Stanley Berenstain created. “The Bike Lesson” was the first to actually call the characters the Berenstain Bears. (Mel Evans/AP)

The Berenstain Bears were inspired by couple’s own family life — their children and then their grandchildren.

“They say jokes don't travel well, but family humor does,” Jan Berenstain told the Associated Press last year. “Family values is what we're all about.”

Galley Cat shared a Scholastic interview with the author about how she and her husband created the series:

We had a zoo-drawing class once a week, and we liked to draw the bears. Once we decided to do books for children, we knew we wanted to do animals. We decided to do bears because bears have always been entertaining – performing bears in circuses and so on. Also, probably the best-known story for children is the “Three Bears,” so it was familiar. They’re sort of like people; the word is called anthropomorphic, and bears are naturally that way. They stand on two legs, their mothers are very good mothers, and so on. When we visited a class a few years ago and gave that answer, one student asked why we didn’t use fish, and our answer was that they aren’t enough like people. Another student said well, then, why not monkeys, and our answer was that they are too much like people.

Fans who remembered reading the Berenstain Bears mourned on Twitter.

I need one of her books to deal with my feelings on this RT @danstamm: Jan Bernenstain has died.bit.ly/xsJdkG

— Maggie Hendricks (@maggiehendricks) February 27, 2012

Very sad about the passing of Jan Berenstain. “The Berenstain Bears and The Spooky Old Tree” was one of my favorite books as a child.

— Todd Ritter (@ToddARitter) February 27, 2012

Saddened to learn my of my favorite childhood authors, Jan Berenstain, has passed away.Remember these classics tiny.cc/yibtt

— Kevin (@KevRI85) February 27, 2012

A previous version of this story accidentally omitted the word “million.” Over 260 million copies of the Berenstain Bears books have been sold, according to the AP.