Start with good pupils, says a report from the BBC about how to characterize a good school. Ratings by parents indicate schools with selective admissions policies must be good. Many schools with high national test scores, while not screening for intelligence, end up giving preference to kids who are likely to succeed.
"If you look up the admissions criteria at some of these schools, you see how this selection - while not ostensibly choosing the brightest pupils - effectively prioritises the more motivated pupils from the more active, energetic and supportive homes.
For example, one Catholic school not only prioritises applicants who make the school their first preference and who are practising Catholics, but also asks them how often they and their children attend Mass, how actively involved they are in the church as, for example, readers, choristers, or members of the union of Catholic mothers.
Another non-denominational Christian school gives priority to pupils who can show active involvement, over a long period, in activities such as choirs, orchestras, sports teams, brownies and cubs.
So, while these schools are not selecting by outright academic ability, or by social class, they are getting the most active, committed, and skilled pupils from the most supportive and involved homes.
It is little wonder that these schools emerge as "good" schools on almost any criteria. I have visited many of them and they are impressive."
It's an interesting way to approach the problem, although it seems to have the same effect as prioritizing admissions based on intelligence or social/economic class.