Complex sentence: Each house block is used for eating dinner/lunch, for students to go at break times and also used as classrooms for teacher without a classroom of their own, they also serve as the location of year group assemblies and similar gatherings.
Split into simpler sentences: Each house block is used for eating dinner/lunch, for students to congregate at break times and is also used as classrooms for any teacher without a classroom of their own. They also serve as the location of year group assemblies and similar gatherings.