Changing classrooms and teachers

All through grammar (or elementary) school we had one teacher and remained in one classroom. Starting with junior high (or middle) school we had a “home room” which we left to go to different classrooms for different subjects taught by different teachers. What was that called? Someone suggested “departmentalization” but somehow that word seems too long for an activity performed by adolescents. I can't visualize any friend of mine ever saying, “Hey, I got departmentalization this year.”