Sam smiles. "Very good. There's also a reservist, who can step in for any position if someone's sick or injured - including during the game - but most game guides don't really mention them."
"The position you're trying out for is Seeker. Seekers are important 'cause the game ends or goes into overtime when the Snitch is caught - basic idea is, Chasers get the quaffle through the hoop, that's ten points. Earning points with the Chasers can be a bit slow if the opposing team's on their game, because the quaffle's reset to the center after each score. Catching the Snitch gets the team who caught it thirty points - and, if the catcher's team ends up ahead with those thirty points, the game ends. If the catcher's team is still behind or tied even with those thirty points, then we go into overtime, and a point goal gets set at the highest current score plus thirty, and game ends when a team hits that."
"The Snitch is a tiny little golden ball that flies quickly and erratically, released five minutes before the start of the game. But it stays within the pitch - and so should you, both because going out of bounds gets our team a penalty and because only the pitch itself has an anti-fall charm. You'll be trying out with a practice Snitch, which can go as slow or fast as I want it to, and with a sports broom." She gestures to the one of the brooms that's hovering unattended. "School doesn't allow players to bring their own brooms, so all practices and games are played on school brooms set aside for official Quidditch matches."