Too many headers lead to brain damage claims study
It's lunchtime at Greensward Academy in Essex and some students are practising their skills playing head tennis.
But these players have already had their daily limit of headers according to some US doctors.
A study of 38 amateur footballers suggests that heading a football frequently can lead to brain injury.
The doctors say the footballers' brain scans showed similar injuries to those that you would see in someone with concussion.
The safe cut-off level is around 1,000 headers a year, which is just a few a day.
An average football can travel at more than 34mph (55km/h) in games, but in the Premier League it could be up to double that.
Other doctors say it's head-clashing rather than contact with the ball that can potentially cause problems.
What Greensward Academy students think
David Ingram, 17, Left Wing
"I head the ball as much as I need to. I'd never pull out of heading.
"You just have to watch out for nasty tackles, they're more what you need to worry about than heading."
Elliot Mooney, 17, Centre Mid
"I understand if people are really young and their brain is still developing, but people have been heading the ball for years without major problems.
"Balls that we use nowadays are much lighter than the ones from years ago, they would have done some damage."
Tommy Waston, 17, Keeper
"This would make me think twice, but it's from America and they don't even play much football.
"I'd have to see some more evidence as you need to be a good header of the ball to be a good player.
"As a keeper, I want people heading the ball to clear the danger. You let it bounce and there could be trouble."