Why were the boys angry with the teacher after Chapter 14 in The Adventures of Tom Sawyer?
The boys were angry with the teacher because of how harshly he was treating them. You can find this in Chapter 21.
The teacher was going overboard in his preparations for the "examination day" exhibition the students were going to put on. The teacher was so worried about how things were going to go that he was punishing them severely for minor things. Twain says that he beat everyone severely except the biggest boys and the young ladies 18 to 20 years old.
That is why they figured out how to have the cat pull off the teacher's hairpiece and show that they had painted the teacher's bald head gold.
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