Original: Singing without accompaniment is called a cappella singing ( although the American Choral Directors AssociationACDA.org discourages this usage in favor of '' unaccompanied , '' since a cappella denotes singing '' as in the chapel '' and much unaccompanied music today is secular ) .
Simplified: Young children 's choirs may be unison choirs ( all singing the same line ) , but older children will sing in two ( SS ) or three ( SSA ) parts or more .