Complex sentence: Since 1999, the morning announcements are done by Clifton News Center often referred to as CNC, it is a 5 minute show done by 2 teachers and about five 6th graders.
Split into simpler sentences: Since 1999, the morning announcements have been done by Clifton News Center often referred to as CNC. It is a 5 minute show done by 2 teachers and about five 6th graders.