Why is Dave worried about his father coming to school in "Split Cherry Tree"?

In "Split Cherry Tree," Dave is anxious about his father's coming to the school because he will stand out as an anachronism at his school, and Dave fears he may "start something."

When Dave and his friends "broke down a cherry tree," their teacher, Professor Herbert, makes the boys pay for the tree; however, because Dave has no money, he has to remain after school and sweep in order to work off his debt. Having to stay late causes Dave to raise his father's ire because he has to do Dave's chores along with his own work that he has done on their farm for that day. Dave fears telling his father why he has been late, knowing that his "Pa" will feel that Dave has been treated differently and unfairly from the other boys.

Just as Dave expects, his father is furious when he returns home late. When Dave tells his father that he has had to stay and work his dollar off after school, Pa wonders why Dave has been singled out--"Poor man's son, huh?"--and why the boys were in Eif Crabtree's orchard--"What kind of a school is it, nohow?" Then, as his father prepares to go to the school, threatening to "...straighten this thing out.... Luster Sexton says, "...a bullet will go in a professor same as it will any man."

Dave becomes extremely worried. Further, Pa accompanies him to school with a gun inside his coat, and Dave, who knows "Pa wouldn't be at home in the high school" with his overalls, big boots, and a sheepskin coat, fears what his father will do to his teacher. He is also embarrassed as Pa pulls out his gun and lays it on a seat in Professor Herbert's office. He is very worried that his father might strike his teacher.

His face was getting red. The red color was coming through the brown, weather beaten skin on Pa's face.

Fortunately, Professor Herbert maintains his composure and he explains well the circumstances of his making Dave work after school. Then, too, he demonstrates some of the things that the students are learning, and Pa is able to even teach Professor Herbert the benefits of a black snake. Later, Pa humbly admits that school has changed since his day.