Parents who send their children to private schools often do so because of the breadth of extra-curricular provision. Sport, drama, adventure, music, the arts - it would be a poor independent school that failed to offer all these.
Observers sometimes forget that boarding schools have greater access to young people's time and that many state school children have an equally rich diet of activities - but they do these things with parents, not with their schools.
The fact remains that out-of-classroom provision in the state sector is limited. While many state schools have a rich variety of activities, few follow the independent model and less than one in ten state schools are thought to have a residential trip as an entitlement for all their pupils. The usual reason is cost, yet the benefits are huge. Study after study have shown the value of this kind of learning, whether it is the Duke of Edinburgh Award, a biology field trip or a youth orchestra. Schools that offer a broad diet of out-of-classroom activities experience a learning gain that is reflected in their academic results.
Concern about safety has also had a negative impact. But, statistically, children are safer on school visits than they are in almost any other context, including at home asleep in their beds. The few fatal accidents that occur are newsworthy precisely because they are so rare.
The perception that schools trips are risky has not been helped by government advice on out-of-school activities that focused almost exclusively on safety. The Department for Children, Schools and Families has for years made available a huge document on health and safety policy on education visits, but said very little about the quality of the experience or the importance of learning outside the classroom.
That situation changed in 2006 when the government launched a Learning Outside the Classroom manifesto. This took the form of a series of pledges, with local authorities and education organisations invited to sign up to show their commitment. There was the promise of a residential experience for every state school pupil, alongside a programme to promote and support out-of-classroom learning.
In October the government will launch a new "badge" scheme to help schools and parents identify high-quality providers, alongside an "out and about" package of help and guidance for schools, parents and providers.
A rich irony for those with long education memories is the strong theme of experiential learning that runs through the guidance. Here is a government document that celebrates hands-on learning of the type derided when Chris Woodhead was chief inspector of schools. This is not a return to the hands-off learning of the 1960s and 1970s that was criticized by James Callaghan for letting children do what they liked "as long as they were happy", but it is about valuing active learning over the accumulation of content.
The question that is unlikely to be answered in October is the thorniest. Who pays? This question concentrated minds immediately after the manifesto launch, when Karen Brush, chief executive of the Institute for Outdoor Learning, said: "I don't see a lot of cash on the table. Over a quarter of young people live below the poverty line. It is vital that financial support is available if those young people are to benefit."
Schools skirt around this issue by asking parents for a "voluntary" contribution to support out-of-school activities. The classic case is the curriculum trip to a museum or activity centre during the school day. The law is clear on this kind of trip: if the activity takes place wholly or largely within or during the school day, no charge can be made and children whose parents might not be able to afford the trip should not be disadvantaged.
But there are many examples of schools where such children are disadvantaged; either because their parents are pressured to pay, or in some cases because the child is excluded from the activity.
Without significant funding the answer may be to define some things as an entitlement and others as enrichment. Schools may not be able to offer a ski trip to every pupil, but they ought to be able to offer an adventurous activity. Schools may not be able to run an orchestra, but all pupils should have the opportunity to sing and perform.
It is vital to free teachers and pupils from the shackles of the classroom. We learn through interaction; by seeing, doing, touching and speaking. We should open the classroom door and introduce children to the world. Sadly, there is no requirement for teachers to be trained in how to do this. That must change.
Phil Revell is chief executive of the National Governors' Association and represents school governors on the National Advisory Group for Learning Outside the Classroom