The eleven-plus (often written 11-plus) was an exam that children in Britain used to take at about age eleven, near the end of primary school. The result decided what kind of secondary school they would go to — a grammar school if they did well, or another kind of school if they did not. It was a high-stakes, one-shot test, and many families felt it sorted children too early and too harshly. In most of Britain it was dropped decades ago, when mixed “comprehensive” schools became the norm. In some areas children still take it, so you may hear parents talking about the eleven-plus as a living thing, not only as history. The name is simply eleven and a bit: the children were eleven, or just turning twelve. It is a British schools-and-life word; you do not need it for Taiwanese or American systems except when you read British books or news. Though actually, people still argue about it with strong feelings — some say it gave bright poor children a chance; others say it stamped children as failures at eleven.