Annie's April Fool's Day Page: Tells about the holiday's history and considers the day from a Christian perspective.
April Fool's Day: Includes hoaxes, pranks, gag gifts, trivia, history, quotes, messages, funny party ideas and April Fool recipes.
April Fool's Day (April 1 ): Offers some history about the tradition.
April Fool's Day or All Fool's Day: Features brief history of the holiday.
Infoplease.com: April Fool's Day Has Serious Origins: Relates the serious origin and history of this light-hearted day.
Lesson Plan - April Fool's Day: Lesson plans for grades 3 and 4 developed as a student project at Utah State University.
Snopes.com - April Fool's Day Origins: In-depth look at several of the legends that surround the origins of the holiday. Includes some modern day examples.
Teachnet.Com / April Fool's Day: Features ideas for teachers to use in the classroom. Includes a short April Fool's quiz.
Wikipedia - April Fool's Day: Hyperlinked encyclopedia article includes the day's origin and information on well-known hoaxes.