Two unusual books -- one pushing the boundaries of literary form, the other offering a new way to play with history -- have won the most prestigious awards in children's literature.

"The Invention of Hugo Cabret" (Scholastic, $22.99), written and illustrated by Brian Selznick, won the 2008 Caldecott Medal as the best-illustrated children's book, while "Good Masters! Sweet Ladies!" (Candlewick Press, $19.99), written by Laura Amy Schlitz and illustrated by Robert Byrd, won the Newbery Medal as the best-written children's book.

Both books are unusual choices. "Hugo Cabret" is the first novel to win the Caldecott Medal, usually reserved for picture books. "Good Masters! Sweet Ladies!," which consists mainly of 22 monologues and dialogues, is one of the few nonfiction books to have won the Newbery Medal; most other winners have been novels.

Called the "Academy Awards" of children's literature, the Caldecott and Newbery medals are awarded annually by the American Library Association. Winning books are "must have" volumes for all libraries and virtually never go out of print, while winning authors and illustrators become instant celebrities in the children's book world.

The market power of the awards also is indisputable. Just hours before this year's awards were announced, Schlitz's book ranked 8,536 in sales on Amazon.com; by the end of the day, it was No. 17.

"Hugo Cabret" was a particularly bold choice by the Caldecott selection committee, which consists of librarians and other children's literature experts. Selznick's chunky book is more than 530 pages long, vastly different from the 32-page picture books that normally win the Caldecott Medal.

But more than half of "Hugo Cabret" consists of full-page illustrations, a fact that made it eligible for the Caldecott Medal. While many previous Caldecott Medal winners are meant for preschoolers, the selection of "Hugo Cabret" -- aimed at readers ages 7 and up -- highlights the fact that the Caldecott Medal can be awarded to any book for readers through age 14.

In awarding the Caldecott Medal to "Hugo Cabret," selection committee members noted that Selznick's book "casts a new light on the picture book form," adding that the book is "filled with cinematic intrigue."

In the book, Selznick blends art and words in a unique way to tell the story of a Parisian orphan named Hugo Cabret, who is desperate to complete the work that his father began on a mechanical man. Hugo believes the mechanical man may have a message from his father, and so he labors on it whenever he has a spare moment from his work to keep the many clocks running on time in the train station where he secretly lives on his own.

But Hugo's life gets complicated when he steals parts for the mechanical man from the toy store in the train station. Reluctantly joining forces with the granddaughter of the toy store owner, Hugo works to solve a mystery that changes his life -- and several others -- for the better.

Selznick's illustrations, done in black and white, are designed to let the reader feel as if he or she is watching a film. Long shots are followed by close-ups as if the reader is watching a camera fill in details of the story. The illustrations are interspersed with text in such a way as to keep the reader moving quickly through the story. While the book is long, it doesn't take a long time to read, making "Hugo Cabret" a great book for reluctant readers as well as those who love to read.

"Good Masters! Sweet Ladies" gives readers an entertaining look at the Middle Ages. Schlitz, a librarian at a private Baltimore school, wrote the book as a way to allow all of her fifth-grade students to perform in a play. To give each student an equal part, however, Schlitz decided to create 21 different monologues and dialogues, which is why her book is subtitled "Voices From a Medieval Village."

"Schlitz adds a new dimension to books for young readers -- performance," said Newbery committee chair Nina Lindsay.

Schlitz knows well the kinds of details young readers like to know and tells, for example, how Lowdy, the "varlet" or dog-keeper's daughter, is plagued by fleas, and how Hugo, the lord's nephew, glories at killing a boar and eating its kidneys "gleaming with fat." Then there's her portrait of Nelly, a "sniggler" or eel catcher, whose ability to overcome her poverty-stricken father's effort to drown her at birth means she is considered lucky.

Medieval history won't interest every reader. But Schlitz's ability to use the monologues and dialogues to create short engrossing character sketches make "Good Masters! Sweet Ladies!" a book that could appeal to a range of readers. (Ages 10-14.)