When Dave's pa was growing up, they only taught
"... readin', writin', and cipherin'. We didn't have all this bug larnin', frog larnin', and findin' germs on your teeth and in the middle o' black snakes! Th' world's changin'."
When Luster Sexton took the day off from work and headed to his son, Dave's, high school, he took a pistol with him. He meant to make things right with the teacher, Professor Herbert, even if it took a bullet to do so. But to Dave's surprise, the teacher and his father soon bonded, and by the end of the day, the two were friends. Professor Herbert had proven that there were germs on Luster's teeth, and Luster convinced the teacher not to kill the black snake. They had both learned from one another and Luster realized that
"He's a good man. School has changed from my day and time."
Luster refused to allow Professor Herbert to "cancel the debt," and he joined Dave in sweeping the classroom. In the end, Luster admitted to the teacher that "I've larned a lot from you." Later that night, Luster
... sat before the fire and told Mom he was going to take her and show her a germ sometime. Mom hadn't seen one either. Pa told her about the high school and the fine man Professor Herbert was. He told Mom about the strange school across the hill and how different it was from the school in their day and time.