I recently had the privilege of visiting two schools in Edinburgh.
They are, geographically, a short distance apart but, in terms of learning environment, level of academic achievement and range of school activities, they could be on different planets.
One school has impressive old buildings surrounded by well-kept gardens and car parks watched over by wardens. The other campus offers a scene from a concrete jungle, with few green spaces and cheaply constructed buildings which have started to disintegrate.
The first school offers a wide range of extra-curricular activities including teams in five different sports. The second school had few extra-curricular activities and no sports teams.
The exam results of the two schools also differ considerably. The proportion of pupils gaining five Higher passes in the first school was more than 70 per cent; in the second it was less than 2 per cent.
So young Scots go to very different schools. The first is one of the capital's grand, fee-charging independents. The other is a local authority secondary school.
It is unfortunate that the gap, or the gulf, between our best and worst-performing schools is so large, and is widening. As a teacher in a school where more than 70 per cent of the pupils qualify for free school meals, I have seen pupils arrive at school hungry, tired and sometimes ground down by problems at home. Concentration is poor and progress limited. Pupils from poorer homes often lack the practical help and support of parents and tutors. Boys in particular suffer from negative peer group pressures and, in some cases, from low teacher expectations.
I have witnessed many highly capable pupils leave their Higher courses to work in low-paid, dead-end jobs that offer an immediate wage for a hard-pressed family.
I have also seen pupils go off to university but drop out almost straight away because they didn't have the social and emotional skills to cope with such an unfamiliar environment. Clearly, too many of our young people are being denied the support they need to realise their full potential.
Then there are the many pupils who can barely read, write and count properly and are so lacking in self-esteem that they are unable to acquire and hold down a job - after 11 years of schooling.
Despite numerous well-intended initiatives, there is an obvious need for some radical new thinking and discussion of ideas, such as the development of skills-based diploma courses, sixth-form colleges and the greater use of one-to-one tutoring. The controversial idea of giving cash rewards to children from poorer families who attain good exam grades is also worth exploring.
Scotland's social and learning gulf is greater than those of most other economically-developed countries. We have much to do to unlock our pool of untapped talent and create a more equitable education system and a fairer society.
John Greenlees is a geography teacher on secondment.