A page in a children's book
A children's book was a type of book that was written for children, rather than adults.
Storybooks which contained children's stories; such as The Kingdom of Elysian were a good example of children's books.
In 2259, Doctor Joseph M'Benga often read a children's book to his daughter called The Kingdom of Elysian. On once occasion, an alien entity transformed the crew of the USS Enterprise into characters from that children's book. (SNW: "The Elysian Kingdom")