Academically, girls achieve as well as boys, even in schools as they are now. If academic achievement were the problem then in those subjects, like English and biology, where girls have for years outperformed boys, one would expect most "top" people to be women. Since this is not the case it suggests that the main obstacle is sexism, and not academic achievement.
So, a major issue is how to tackle sexism, while also keeping up academic achievement. There are many ways of doing this, but a primary one must be to promote understanding of, and communication with, the other sex. This is to contribute to the development of a realistic picture of "masculinity" and "femininity", so young people have a secure psychological identity. To know "Self", one has to know other. For example, a girl has to understand "masculinity" to be secure in her "femininity", since the two understandings are inseparable. Sexual identities are forged at adolescence.
Schools and society must aim for pupils to accept differences - sexual, racial, religious - and to celebrate them. The more one is secure in oneself, the more one can do this. Unless the sexes are together, "knowing" is difficult, since it encourages those psychological processes of projection that see problems in others rather than oneself.
The more one is afraid or "unknowing" of the other sex, the less one can celebrate difference. Separation also encourages misunderstandings. For example, if girls have to develop a concept of "maleness" without boys being around, it is easier to see them as "different-from-girls"; then "maleness" can become "notfemaleness". This reinforces difference rather than, through dialogue and example, realising the complexity of similarities and differences that exist.
Communication between the sexes is essential, and there is no other area of life (for example, race or religion) where anyone thinks that separation is the way to engender understanding.
Indeed, separation at adolescence, when ideas on being male and female are undergoing such changes, will almost certainly contribute to sexism. Especially at adolescence, it is important that girls and boys learn to work together as friends and companions, engage in dialogue to understand each other, and realise that them getting together is not necessarily sexual.
Separating them into single-sex schools does the reverse and "says" that boys and girls do not work together, reinforces myths about sexual differences (why else separate them?) and encourages a sexual reading for other-sex meetings.
Separation also provides a psychological shelter for those pupils and teachers who have sexual insecurities. Adolescence is a period where boys and girls are likely to be insecure, and require help to enable them to face up to, and work through, those insecurities. Separation can enable those who need help to avoid self-development, leaving the hang-ups to emerge later.
It is easy for a sexually insecure boy to say, "Girls can't do science", and so confirm their masculinity. Such statements can be confronted when girls are in the class doing well. Co-education can provide a framework where challenges to sexism can be made and girls and boys learn that they can work together, and that that is normal. Similarly, single-sex schools can contain male and female teachers, but why should a teacher who enjoys the company of, and working with, the other sex choose to teach in a single-sex school?
This is not to say that co-educational schools will be easy to teach in, but that life will be more interesting, harder, and more will be achieved. Co-educational schools have much to contribute towards men and women getting on well together, having good sexual relationships, and treating each other as people. What is needed is teachers who are committed to the struggle and to finding ways of changing co-educational schools to make them even better places.
Brian Matthews is a lecturer at Goldsmiths' college and is researching ways of enabling girls and boys to communicate while learning.