Why do the children of old schools seem happier in Margie’s imagination?

Correct answer: Because they learned with a human teacher and classmates

The governing idea is that happiness in education can come from shared human experience, not from the absence of study. After discovering the old book, Margie imagines children learning together in a schoolroom, meeting a real teacher, talking to one another, and helping one another with work. This contrasts with her solitary lessons at home, where the mechanical teacher provides instruction without companionship. Having less technology may be part of the historical contrast, but it is not the deepest reason for the imagined happiness. The children are happy because learning is social, guided, and shared. Therefore, option D is correct.