Complex sentence: The grade 12 seating areas are an unwritten rule, under the English block, students wait many years to ascend to these areas and they are the centre of the Leavers' Week celebrations.
Split into simpler sentences: The grade 12 seating areas are an unwritten rule. Situated under the English block, students wait many years to ascend to these areas and they are the centre of the Leavers' Week celebrations.