In a fight almost anything goes. It almost reaches the point where you stop to apologize if a chance blow lands above the belt.
I think we owe it to children to let them dig their knowledge, of whatever subject, for themselves out of the "fit" book; and this for two reasons: What a child digs for is his own possession; what is poured into his ear, like the idle song of a pleasant singer, floats out as lightly as it came in, and is rarely assimilated. I do not mean to say that the lecture and the oral lesson are without their uses; but these uses are, to give impulse and to order knowledge; and not to convey knowledge.