Some of the best minds in the field of British education have been thinking this over and have recently presented their findings.
Professor Patricia Broadfoot, a former Professor of Education and now vice-chancellor of the University of Gloucestershire, argued that the evidence from international studies showed that "the highest quality teaching and learning comes when we have the greatest autonomy for the teacher and the learner".
Professor Debra Myhill, from Exeter University, argued that while good subject knowledge and intellectual ability were both important, they were not "sufficient" to be a good teacher.
The crucial ingredient, she argued, was a teacher's ability to reflect on his or her own performance and then to change it.
The third expert is Professor Mary James, from the Institute of Education. One of her top 10 requirements was that the teacher should "promote the active engagement of the learner".
Citing studies that showed the academic gains from children working collaboratively in groups, she argued: "If learners are not involved in their learning, they do not learn".
Read more about the report here.