In the early 20th century, Franklin K. Matthiews, the librarian of the Boy Scouts of America, embarked on a nation-wide tour to advocate for better standards in children’s literature. At the time, relatively few kids’ books were published each year—in part because printing color illustrations was expensive—but Matthiews was a firm believer in the importance of children’s literacy. His advocacy led to the launch of Children’s Book Week in 1919, an annual celebration of books for little ones.

The initiative still takes place today, and in honor of its 100th anniversary last week, the Library of Congress digitized a collection of dozens of children’s books published prior to 1924, reports Perri Klass of the New York Times. Some of the newly digitized stories are classics that will likely be familiar to modern readers—like an 1888 copy of Rip Van Winkle or a 1911 edition of The Secret Garden—while others have not stood the test of time quite as well. Before The Cat in the Hat, for instance, there was The Cat’s Party, an 1871 picture book about festive felines.

The oldest book in the digital collection is A Little Pretty Pocket Book, which is considered to be the first book written specifically for children. It was originally published in 1744 by John Newbery, the pioneering English bookseller who is credited with carving out a market for children’s literature. The Library of Congress’ edition was printed in 1787.

“Well into the 19th century, most of children’s literature in America came from Britain,” Jacqueline Coleburn, the rare book cataloger at the Library of Congress, tells Klass. “It wasn’t till the 1830s and 1840s that we really focused on producing American books.”

When they did take off in the United States, the reading material was often as creative and as fun as the books tykes read today. An 1863 copy of Red Riding Hood was cut in the shape of a girl with wolf wrapped around her feet. The Slant Book, which was published by Harper & Brothers in 1910, follows a little boy as he gleefully causes havoc careening down a hill in his pram. According to Atlas Obscura’s Jonathan Carey, the book was published in the shape of a rhombus to convey little Bobby’s race down the slope. In 1912, American illustrator Peter Newell published The Rocket Book about a “bad kid” named Fritz who sends a rocket flying through the floors of an apartment building. There's an intentional hole on every page of that book to reflect the rocket's movement through the building. “It’s so tactile and yet so old,” Lee Ann Potter, director of the learning and innovation office at the Library of Congress, tells Klass.

Although the collection highlights the joyful commonalities between children past and present—kids today will surely get a kick out of Fritz’s rocket carrying away an old man’s wig—the books can at times feel jarringly out of sync with modern sensibilities. They aren’t diverse, for one thing, and sometimes reflect problematic notions of gender. A Little Pretty Pocket Book, for instance, was once sold with a ball for boys and a pincushion for girls.

“They are historical documents which reflect the attitudes, perspectives and beliefs of different times,” the Library takes care to note.

The institution’s experts hope that parents, instead of shying away from the books’ uncomfortable tropes, will use them to teach their children important lessons. As Potter tells Klass, “We’re celebrating the fact that these books provide us with the opportunity to have conversations about what is appropriate or inappropriate, that they help us understand a different time.”