Final answer:
The chapters from the Harry Potter series not set during Christmas are 'Flight of the Fat Lady', 'The Polyjuice Potion', and 'The Beetle at Bay'. 'The Yule Ball' and 'The Mirror of Erised' do involve Christmas.
Step-by-step explanation:
In the context of the Harry Potter book series, the chapters that do NOT take place during the Christmas period are:
- Flight of the Fat Lady: This chapter does not involve the Christmas season; instead, it deals with the aftermath of a Halloween event.
- The Polyjuice Potion: The events in this chapter take place leading up to Christmas, but the main event, the transformation by the Polyjuice Potion, occurs before the holiday.
- The Beetle at Bay: This chapter focuses on Harry Potter's life at Hogwarts and his experiences outside of the Christmas timeframe.
The chapters The Yule Ball and The Mirror of Erised do include events that are centered around the Christmas period. The Yule Ball is specifically a Christmas-time event in "Harry Potter and the Goblet of Fire", and Harry discovers the Mirror of Erised during the Christmas holidays in "Harry Potter and the Sorcerer's Stone".