I believe that this question is asking about events that begin in chapter 9. This chapter begins with Kit and Mercy starting to teach school at the Wood's home. Kit is not nearly as patient as Mercy, but she is good at teaching the older kids to read through her usage of "tricks" and rhymes. The two teach eleven total children, from ages four to seven.
At one point in the teaching day, Kit decides to tell the story of the Good Samaritan. Kit is fairly adept at telling stories, but she decides that in order to make the story more real, tangible, and fun for the kids, the kids will act out the various parts of the story. Mercy is not fully on board with the idea. Playacting in a Puritan school is not something that is done.
Unfortunately, the entire idea goes from bad to worse. The boys start goofing off instead of taking it seriously, and that is the moment that Mr. Eleazer Kimberly and Reverend John Woodbridge enter the classroom. Kit takes the blame, and the men are very disappointed.
"Play-acting! And with the Bible."
Reverend Woodbridge stared incredulously at Mercy. "What could you have been thinking of, Mercy, to allow such a thing?"
"I am shocked and disappointed," he said sternly. "I had heard such excellent reports of your school."
The punishment is quick and severe. School is dismissed for the day and the following day. Additionally, Kit is permanently dismissed as the teacher, and the two men will "consider seriously" whether or not Mercy should be fired as well.