Gender is important in school choices but it is not as simple as it may seem.

• • Single-sex. A number of independent schools are single-sex, including many of the heavyweights (academically and socially).

• • Co-education. The majority of schools are now co-educational. Most were originally single-sex schools that have adopted co-education in the past 20 years, although a few have been co-educational since their foundation.

• • Mixed sixth. Some schools provide single-sex teaching up to 16 but are then co-educational at sixth-form level. This trend started with boys’ schools accepting girls into the sixth form but now a number of girls’ schools are similarly accepting boys at 16. Sometimes it has proved to be a phase in the transition of a single-sex school to co-education but a number of these schools are committed to remaining single-sex up to 16.

• • Diamond model. This is where brother and sister schools have a common co-educational junior school, from which pupils move to one of two single-sex secondary sections, and then on to a common co-educational sixth-form at age 16. There are usually strong links for extra-curricular activities between the two schools during the single-sex period.

So what are the arguments?

• • Those in favour of single-sex education cite the generally higher achievement in public examinations by both boys’ and girls’ schools in comparison with co-educational schools. They believe that adolescents perform better if they are allowed to develop at their own pace, without the distractions of the opposite sex and without unhelpful gender-typing (eg girls don’t do hard science).

• • Those in favour of co-education believe that, in a world where the sexes have to work together, there is no justification for educating them separately, and opportunities such as boys learning to cook or girls joining the CCF are more likely to be available in co-ed schools.

• • Those in favour of single-sex teaching to 16, followed by a mixed sixth see as being the best of both worlds and can make a sensible stepping stone from single-sex education to the hurly-burly of university life. But girls entering the sixth form in a boys’ school (or boys to a sixth form in a girls’ school) need to be mature for their age and have both a sense of humour and a robust character.

Then there is the detail. Some single-sex schools have a range of activities with other schools, so pupils can play in orchestras, take part in debates and outings etc with pupils of the opposite sex; others are depressingly isolated.

If a school has become co-educational recently, look carefully to see if the transition has been handled successfully. This requires considerable adjustments, not only to the physical environment but to the social structures, sports offered and school ethos. Some schools manage this better than others.

In practice – as so often – different approaches will suit different children.