Moshe Grylack repeats a wonderful lesson from our generation’s teacher, the Chazon Ish:
There was once a seven-year-old boy who was playing wildly in the room where the Chazon Ish was learning. A talmid who was present sternly warned the boy to stop his noisy behavior, threatening to tell the boy’s rebbi on him. The Chazon Ish quietly told his talmid that he had just transgressed the Torah prohibition of hurtful speech, that it is forbidden to cause anguish to a fellow Jew, and a threat like that causes anguish to a child. There is nothing in the pasuk, the Chazon Ish commented, that differentiates between a child and an adult.
In response, the talmid asked how to reconcile this with the need to be mechanech the child. The Chazon Ish answered that there was no need for him to be mechanech the child; the mitzvah of chinuch was the responsibility of the child’s father.
… [T]he Chazon Ish went on to advise the talmid that if the child was disturbing him, he could go and learn in another room — but not to tell the child to stop playing.
Note: The Chazon Ish, a walking Sefer Torah, made sure to correct the man quietly.