The Tok and Teo families are a model of traditional harmony, with three generations gathered under one roof, enjoying each other’s company over slices of fruit and cups of tea on a Saturday afternoon in Singapore. There is only one problem: The youngest and oldest generations can barely communicate with each other. Lavell, 7, speaks fluent English and a smattering of Mandarin Chinese, while her grandmother, Law Ngoh Kiaw, prefers the Hokkien dialect of her ancestors’ home in southeastern China. That leaves grandmother and granddaughter looking together at a doll house on the floor, unable to exchange more than a few words.