They are playing quidditch! The sport based off the broomstick sport of the Harry Potter series. The third photo is a seeker(yellow headband) trying to catch the snitch(the snitch sock with the ball). The players with the white headbands are chasers which attempt to shoot the quaffle(the slightly deflated volleyball) into one of three hoops. The green headband marks a keeper which is responsible for guarding the hoops but also does what chasers do.
If you fall off your broom, you have to run back and touch your hoops before resuming play. The black headband denotes the beater position in which they use dodgeballs to knock players off their broom(like dodgeball, if you're hit, you are out.)
As shown here with the purple bludger thrown in order to void the shot made by the chaser.
It's a full contact co-ed sport. It gets rough at times but it's a ton of fun.
I also play quidditch but our school's team isn't competitive.