Roller derby is a contact sport played by two teams of five members roller skating counter-clockwise around a track.
Game play consists of a series of short match-ups (jams) in which both teams designate a jammer (who wears a star on the helmet). The jammer scores points by lapping members of the opposing team. The teams attempt to hinder the opposing jammer while assisting their own jammer—in effect, playing both offense and defense simultaneously.
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Junior Roller Derby is very similar to the adult sport, although games or jams can be played at one of three levels (level 1, level 2 or level 3). Each level corresponds to levels of skill and contact players are allowed to use.