NEW YORK--(BUSINESS WIRE)--Starting in September, schools across the country can submit an a cappella version of The Jackson 5 hit “I Want You Back,” for a chance to win Macy’s All-School A Cappella Challenge. Students, faculty and staff of schools nationwide can enter a video performance of the song, unaccompanied by any music or instruments. Three $25,000 prizes will be awarded – one to a school in each of the following levels: elementary through middle school level, high school level and col