A good question for The Devil’s Arithmetic would be: Why did Hannah change her opinion about Passover? The answer is that Hannah was transported back in time to the Holocaust.
This is a good question because Hannah makes a big change of heart from the beginning of the book to the end. At the beginning of the book, she says she is tired of holidays that focus on remembering. She finds the Seder ceremony boring. Perhaps this is the reason why she finds herself magically transported to the Holocaust. She becomes Chaya, her Hebrew name, and lives the life of the girl she was named after.
Hannah finds that she does want to remember. Remembering is imporant.
[She] realized with a sudden awful panic that she could no longer recall anything from the past. I cannot remember, she whispered to herself. I cannot remember. She's been shorn of memory as brutally as she'd been shorn of her hair... (p. 94)
Hannah experiences almost all of the horrors her namesake did, but when it comes to the time when she sacrifices herself, she returns to the present with a much better appreciation of the past.