One player practises keeping the ball in the air for minutes at a time. Another practises kicks at goal from all angles. Both players are improving their ball skills. So which one will contribute most to the team? In any walk of life, if you improve an individual's skills, the organisation will benefit.
Jill Wilson, head of Oathall Community College in West Sussex, says: "We believe improvement involves multiple aspects of the school - whether it's behaviour, achievement or whatever, professional development will link into it."
She adds that it is no longer simply a question of "teachers going on courses". Certainly, teachers once looked through a menu of courses and picked what suited them. But now, in well-managed schools there are portfolios and performance management interviews, and the whole business is much more planned. At its best, this approach leads to virtually everything that a teacher does - courses, subject responsibilities, action research - becomes integral to professional development and overall school improvement.
Usha Devi, deputy head and leader of staff development at Adderley primary in Birmingham, says: "Our school is a learning community. We see professional development as part of the culture of the school, informing everything we do."
John Preston, head of Sir Charles Parsons, a special school in Newcastle upon Tyne, believes that staff development is now much easier than it was - because there are simply more opportunities.
"In the past we relied on what the authority provided," he says. "Now there is increased funding and we can look to external providers, and focus on needs."
At the level of classroom practice, there is a strong body of opinion in favour of a subject focus, particularly for secondary teachers. So it becomes not just "learning to use an interactive whiteboard" but also "learning to use an interactive whiteboard in geography lessons".
The Association for Science Education advocates this approach. Its in-service director, Malcolm Oakes, says: "Professional development is enhanced if it is placed firmly in a subject context. We have found that to be significant in the success of all our work."
The advantage in the training programme at the ASE is that staff development that is focused on teaching a subject benefits the teacher and the department.
But subject focus is not the be all and end all. The PE teacher may be supported through a management diploma or a masters degree, even though there may be no immediate benefit in the gym. Heads and governors like their staff to be well qualified, partly because they are enlightened employers, and partly for how it looks in the brochure - and crucially because they want bright, thinking teachers around them.
John Preston says that at Sir Charles Parsons school, "the governors have a policy of supporting staff who study for higher degrees.
"Their work may not directly link to the priorities of the school improvement plan, but we have an obligation to support them in developing professional skills."