Unlike a regular game, or "bout," the scrimmage included six men and two girls. The men were either Iowa City clinicians or local men training to be referees.A regulation game consists of two teams that each field 4 blockers and 1 jammer per jam. There are all womens, all mens, and co-ed teams. It depends on the rule set you are following.
Prior to the actual scrimmage, the referee checked each player for foreign objects. He mostly disallowed ornamental pieces of metal that could accidentally injure someone if two players collided.
You left out, he was checking safety equipment.
One player on each side, designated as the "jammer" and wearing a star on her helmet cover, is allowed to score by earning a point for each member of the opposing team that she passes on the rink.
It's called a track, and the jammer can also score on players that did not make it onto the track as well as players in the penalty box.
The other players link up and form a "jam" to block the opposing jammer from passing them or to help their jammer advance. The teams play offense and defense simultaneously.They form a pack, not a jam.