This time it was broken water pipes which sent students home early on Tuesday.  Elementary school students were first sent outside to the sound of the fire alarm and then were held in the gym while damage was assessed and a plan was devised to send the students home in an orderly way.  About one-third of the classrooms in the K-4 and specials area had broken ceiling tiles and puddles on the floor because of the pressure induced breakage of copper pipes.  Mrs. Walker reported that the sudden spraying of water and the collapsing of ceiling tiles was at first frightening to both students and teachers.  Fortunately, maintenance head Dave Gordon was nearby.  It didn't take him long to find and close the necessary valves to stop the water.