India, Oct. 6 -- In a room measuring ten feet by ten feet in Delhi's Jahangirpuri, a boy who had not begun to speak started forming words. Both his parents were deaf and could not speak, and it had been assumed the boy could not either. At the creche built into that room, a mirror had been fixed at his eye level. Each day he watched himself and the other children shape sounds, copying the movement of their mouths. Over weeks, the words came. He was not deaf. Something in his home had kept him silent, and the room drew him out.

That mirror cost almost nothing. This is the case architect Swati Janu made at a recent Bachpan Manao masterclass: The spaces we build for our youngest children shape how they learn, and even a modest room can be t...