Complex sentence: The key to this integration was often argued to be the social events that occur throughout the academic year, including a Christmas Meal, a Summer Ball, a Quiz Night and a Pizza and Bowling Night.
Split into simpler sentences: The key to this integration is often argued to be the social events that occur throughout the academic year. The many social events held throughout the year include a Christmas Meal, a Summer Ball, a Quiz Night and a Pizza and Bowling Night.