Answer:
The phrase "to sink through the floor" illustrated that Addie is embarrassed by her lack of knowledge.
Step-by-step explanation:
The story was about a young girl who moved to a different environment. She was treated unfairly by her classmates. They were asked to recite a poem and she couldn't.
Since she wasn't able to recite the poem,
her classmates made fun of her. She was embarrassed and felt she could sink through the floor. She was embarrassed by her lack of knowledge.