This week (September 24 through October 1, 2011) is the American Library Association's Banned Books Week, an "annual event celebrating the freedom to read and the importance of the First Amendment." We've all heard about books like Lolita and The Awakening being banned, especially from schools, for overly sexual content; other books are banned—or at least challenged—for violence, curse words, being "obscene," or otherwise containing content deemed objectionable or dangerous. But some challenged books are more surprising than others...

1. Merriam-Webster Collegiate Dictionary

You'd think a dictionary would be one of the least objectionable books possible, but even the classic Merriam-Webster, the standard for spelling bees across the country, was challenged last year. The Union School District in Menifee, CA, pulled the dictionary off shelves when a parent complained about the explicit definition for "oral sex." A committee of parents, teachers, and administrators was formed to review the Merriam-Webster, ultimately deciding to leave the dictionary available for use by fourth- and fifth-graders at Oak Meadows Elementary School, though parents can choose to have their children use an alternative dictionary.

2. Anne Frank: The Diary of a Young Girl

by Anne Frank
One of the most widely read—and beloved—books discussing the Holocaust, Anne Frank's diary was actually challenged last year for "sexual material and homosexual content." After "a hailstorm of criticism online attention" following reports that the book would no longer be used in Culpeper County, VA, schools, the superintendent said Frank's diary will remain part of English classes, but may be taught at a different grade level than previously.

3. Eyewitness Books: Horse

by Juliet Clutton-Brock
This book is one of the photo-packed "Eyewitness Books" meant to inform readers about a given subject; it's filled with info about the behavior and history of horses, including zebras and donkeys. It was challenged in 2004 at Smith Elementary School in Helena, MT, by a parent concerned that it "promotes evolution." The school kept the book on the shelves.

4. Freakonomics: A Rogue Economist Explores the Hidden Side of Everything

by Steven D. Levitt and Stephen J. Dubner
This economics smash hit was challenged in 2006 in Illinois' Northwest Suburban High School District 214. One board member, having only read excerpts of the Freakonomics online, objected to the book's argument that legalized abortion led to a lower crime rate. At a board meeting to determine the fate of Freakonomics and 8 other books, the original complainant was the only board member to vote for the books' removal from the reading list. To celebrate, Dubner and Levitt gave away 50 free signed copies of the book to District 214 students.

5. The Junie B. Jones Series

by Barbara Park
This kids series has been challenged more than once by parents. In 2006, Junie B. Jones and Some Sneaky, Peeky Spying was challenged in Wake County, NC, for not adhering to family and social values; parents have complained about other books in the series for Junie's spelling and grammar skills, or rather her lack thereof, her troublemaking, and her mouthiness.

6. Notre Dame vs. the Klan: How the Fighting Irish Defeated the Ku Klux Klan

by Todd Tucker
In a highly publicized situation in 2008, Indiana University-Purdue University Indianapolis (IUPUI) found an employee guilty of racial harassment for reading Tucker's book in a public area. The decision was surprising since the book—an account of a 1924 clash between Notre Dame students and Ku Klux Klan members—isn't favorable toward the Klan, but was still viewed as offensive to the employees black co-workers because it "related to a historically and racially abhorrent subject." (The initial complaint was based solely on the cover.) After first being ordered not to read the book in the presence of his co-workers, the employee later received a letter stating that "no determination could be made as to whether his reading choice was intentionally hostile," and no disciplinary action was taken. Following involvement by the ACLU of Indiana, IUPUI stated its "regret this situation took place" and its commitment to freedom of expression; according to the university, there is no record of the incident in the employee's file.