Aiming to revise for four hours but only managing 10 minutes is no use at all. Get them to start with 10 minutes only. They should then have a break for 10, then work for 10 minutes more.
Anyone can do that. But when working they should really work, and when not, they should really relax. The two don't mix.
That's 20 minutes' work in a 30-minute period - much better than 10 minutes in four hours. The working periods should then be extended to 30 minutes or so - but the breaks stay fixed at 10.
Next they could ease in an extra half-hour of work a day. By getting up earlier or taking less time over lunch, they could gain an extra two-and-a-half hours over five days. That could leave an evening free.
Encourage them to ask you if they're stuck. They probably see you as more approachable than their parents - but only marginally. So don't push it.
George Turnbull is the Qualifications and Curriculum Authority's exams doctor. He can be contacted at email@example.com. You can also visit his pages at www.qca.org.ukalevel The 20-minute rule
Twenty minutes' aerobic exercise boosts serotonin levels, which aids relaxation, supplies oxygen to the brain as well as muscles, and provides a mental break.
But pupils should not be too laid-back while revising. Research suggests that people can recall material better in circumstances resembling those in which it was originally learnt. For instance, people who memorised material when they were drunk recalled it better when re-intoxicated than when they were sober.
Not an invitation for pupils to hit the bottle while revising, but to revise while sitting at a desk or table rather than lying in bed or by the pool. And advise them to keep the music down - they won't have that in the exam hall.
When learning material, try and make it memorable by building up images that appeal to as many senses as possible.
Make them bright, smelly, sexy, and noisy and they should stick in your head. Bizarre or comic associations are easier to recall.
Stephen Briers is a psychologist and TES Magazine columnist