I'm new to skating derbies, so bear with me as I describe what
is happening here. The two girls in the back of the queue wearing
stars on their helmets are called jammers. Jammers start at the
back of the pack and try to work their way to the front during a
jam (2 minute period during which points are scored). The girls with
the stripes on their helmets are called pivots. They stay at the
front of the pack and push their jammer forward when the jammer
works her way to the front of the pack. The rest, in the middle,
are blockers. Blockers make holes for their own jammer and block
the opposing team's jammer.