How does Luster "educate" Dave about his future in "Split Cherry Tree"?

Luster Sexton "educates" Dave about his future by explaining both by words and by example that Dave must "go on to school" so that he will not become "a dead leaf" like him. Dave must also be honest and pay his debts, whatever they may be, Luster tells his son. Thus, he also educates Dave about having integrity, especially when he expresses regret about his incorrect opinions of Professor Herbert and the school.

Dave's Pa first learns that Dave is late because his teacher, Professor Herbert, has made him stay after school to work off a debt incurred when he and some other boys split a farmer's cherry tree that they climbed to catch a lizard. Hearing this, Luster becomes angry since he perceives "bug larnin', frog larnin'....and breakin' down cherry trees" as frivolous and not appropriate to schooling. Then, when he learns that Dave is the only student who has had to stay because the other boys had the money to pay their share of the cost of the tree, Luster is even angrier. For, he feels that the teacher has discriminated against Dave since he is poor. Feeling his family pride under assault, Luster vows to go to the school:

"I'll straighten this thing out myself! I'll take keer o' Professor Herbert...He ain't go no right to keep you in and let the other boys off jist because they've got the money!...A bullet will go in a professor same as it will in any man. It will go in a rich man same as it will a poor man....

The next day, then, Luster accompanies Dave to school. There he meets Professor Herbert, who is at first intimidated by Luster's size and the sight of his gun. However, after he demonstrates to Luster what the class has been doing and he is willing to learn from Dave's father about the value of black snakes, the two men get along. After school, Dave's father insists upon helping Dave sweep and pay off his debt, telling Prof. Herbert, who has offered to cancel this debt, "We don't do things like that....We don't want somethin' fer nothin'." As they sweep together, Pa apologizes to Dave, saying that he has misjudged school because he is behind the times, a "dead leaf."