What was the purpose of the Halloween pageant? What practical joke had persuaded the grown ups to have an organized event?

The Halloween pageant was meant to keep children out of trouble.... to give them an organized Halloween. The event that proceeded and made this event inevitable was the prank played on the Misses Tutti and Frutti Barber the year before. While the women were sleeping, a group of children celebrated Halloween by sneaking into thier house and moving all their furniture into the basement. In order to stop a repeat of this type of event, Maycomb decided to host a pageant that would involve everyone.