The second part of chapter 15 might be thought of as the whiplash point. Lavinia, the head Mean Girl, has told tales on Ermengarde and sent Miss Minchin in an unprecedented second trip up to the attic to catch the girls in the midst of their pretend princess banquet. The extremity of MIss Minchin's anger can only really be understood as sparked by the disruption Sara brings to the proper order of things. Viewed from a distance, why should it matter that Ermengarde chose to share her food "care package" with Sara and Becky? Why should it matter that she shares her books?