How do adults learn? Ignore the muttering from the disgruntled tutor in the corner who's just seen his budget slashed. And, honestly, it's not a trick question. Lifelong learning is a fine principle and a lofty goal, but what does it mean in practice? Beyond the issues of funding, courses and structures, understanding the way we learn and how we therefore need to teach could be at the heart of ensuring it becomes a reality.
We now know quite a lot about andragogy, as the American educationist Malcolm Knowles called adult learning when he titled his book on the subject in 1984. Since then, science has filled in even more of our understanding of how the brain works and what happens as we age.
But is adult learning very different from the learning we do as children? And do we need to rethink our approach to adult learning - or even to the way we teach children in school?
The answers could lie in two directions - a switch to helping people learn to learn from an early age; and a new relationship between teacher and learner.
Malcolm Knowles suggested the difference between adult and child learners was that adults were self-directed, came to learning voluntarily and brought with them a lifetime of experiences - factors that required a different approach to teaching. They were also already used to problem-solving in their everyday lives.
His response was to suggest a teaching style that was more practical and hands-on, with clear, short-term goals and which took full account of the learners' experience.
But some people question whether we need to go a stage further. The key to bringing people back into learning - and keeping them there - is to view it as a collaboration rather than a service.
In south London, Lewisham college will later this year embark on a project it is calling Teach Too - inviting older people not only to return to learning but to share their skills as well.
"We want to value their learning, not make them unskilled again," says Lewisham's principal, Ruth Silver. "One issue about bringing older people back in is you quite often rob them of the skills they already have. That doesn't do a lot for their self-esteem."
She envisages a mini-trade in skills: "I'll do a couple of hours for you in this instead of paying for that computer course, for example." Some might teach courses themselves, while others might work in the creche or provide other services. A similar scheme for retired staff, Elders, is already being piloted.
Meanwhile, the college is accrediting adults for work they do as mentors, study buddies and the like. Ms Silver says the aim is to give "dignity" to older learners.
That sense of a (more) equal relationship is likely to be something we see more of - not least because future adult learners will have gone through an education system based on personalised learning.
But what of the way the brain works? Is there anything intrinsic to ageing that requires new methods of learning? "The biggest myth about ageing is 'use it or lose it'," says Bill Lucas, former chief executive of the Campaign for Learning and author of a new book on lifelong learning. "There are very few things senior citizens can't do; it just takes them a bit longer."
The latest thinking points to two key stages in the brain's development: at around 50, it begins to lose the ability to make new connections; and past 70, people find it harder to retrieve memories. But the brain's performance can be improved simply by exercise.
"If I were redesigning the lifelong learning curriculum, I'd have much more sensory stimulation and much more moving around," Mr Lucas says. "Even very simple things like getting everyone to stand up every so often is thought to send 20 per cent more oxygenated blood to the brain."
Memory problems are also surrounded by myth, he says. Neurodegenerative diseases such as Alzheimer's affect only a small minority. Most people retain the ability to store information - it's retrieving it that becomes difficult. And as anyone with grandparents knows, long-term memory is often excellent even as they lose their spectacles yet again.
The answer is to teach them thinking and memory techniques at an earlier age. And this is already happening in schools. The next generation of young people are more likely than ever to know how to learn.
One future would see providers adopting an armoury of techniques - just as classroom teachers do for mixed-ability classes - at least until diffident learners have been eased back into learning. Early lessons would be tailored for the theorists, or those who like to roll up their sleeves and plunge in.
But that brings us back to the relationship between learners and teachers.
"We've begun to accept that exercise, diet, lifestyle all have a part to play in health," says Bill Lucas. "The relationship with your adult learning deliverer needs to be like your relationship with a GP you know well - whose job isn't just to give you pills but to help you find ways of living sustainably. That's the thinking we need to apply to adult learning."
Bill Lucas's guide to lifelong learning, 'Discover Your Hidden Talents', will be published this spring by Network Educational Press