How did teachers teach children in old times?

Correct answer: By being directly with children

The governing idea in Isaac Asimov’s “The Fun They Had” is the contrast between traditional human teaching and future mechanical instruction. In the old kind of school, a teacher was physically present with the children, explained lessons, responded to their questions, and guided their learning. Therefore, option A is correct: teachers taught by being directly with the children. The mechanical teacher in the story works alone in a child’s home and cannot provide the same personal classroom experience. Options B, C, and D are incorrect because hiding in a machine, merely lighting a screen, or abandoning children does not describe teaching.