We chose a single sex school for our daughter which was confirmed by reading the report by the Girls School Association, stating many points, of which:
i) girls are less catty in girls schools as it is the presence of boys which encourages showing off and a need to impress;
In my experience girl are far MORE catty in a girls school - the alpha female problem
ii) ability to do more subjects and activities which otherwise would be seen as boys only, ie lighting in the school play, and the recent reports that physics/science are frequently dropped by girls;
Evidence? Again, in my experience this is just not true - I loved beating the boys at maths and physics! The data I have seen does not bear this out - it may
have been true 50 years ago.
iii) less peer pressure to do girly subjects - all subjects are open to them from this perspective. Similarly, girls are not wanting to do PE because of it makes them less attractive to boys.
The gender imbalance is out-of -date (when was this research?); more girls at medical school. What are girly subjects anyway?! Schools don't look at subjects like this anymore - PE is taught separately so this is not valid
(iv) no oggling at boys across the classroom at a young age, they get on with what they should be doing, ie learning. They can socialise with boys in the 6th form or outside of school with various clubs, etc.
We did not look at boys in our year group - nor does that happen in my experience of teaching for some of my career in a mixed school.
(v) no need to plaster themselves in make-up, wear ultra short skirts, etc as there is no-one to benefit.
Girls compete in a singer gender school as well!
All the arguments have counter points of view ... it is a personal preference but interestingly not one open to parents in a Bucks Upper school!