US universities are among the best in the world. Since World War II, American scientists --- mostly working in universties or colleges --- have won more than half of all Nobel Prizes in physics and medicine. Foreign students rush to the United States by the tens of thousands. Last year they earned more than one quarter of the doctoral degrees awarded in the country. Yet while American universities produce the great research and great graduate program, they sometimes pay little attention to the task that lies at their very core: the teaching of undergraduate students. With the increase in fees, educators feel obliged to improve undergraduate teaching. In speeches and interviews the nation's higher educators have rediscovered teaching. Robert Rosenzweig, president of the Association of American Universities,  said,  "Our organization was never very concerned about teaching. In the last 18 months, we have spent more time on undergraduate education than on any other subject." Despite such promising efforts, no one doubts that research still outranks teaching at some of the leading universities, not least because it is a surer and faster way to earn status. Some people don't think it has to be that way. They argue that the reward system for college faculty can be changed, so that professors will be encouraged to devote more time and effort to teaching. They say that they are beginning to believe that the first ten years of the 21st century may come to be remembered as the decade of the undergraduate. That would bring it full circle. For more than two centuries after the founding of Harvard College in 1636, the instruction of undergraduate students was an essential condition of American higher education. It is implied in the passage that about 200 years ago undergraduate instruction   _  .
began to change all of a sudden was already threatened by research work was the central part of higher education began to be neglected in most universities