A knock-on occurs when the ball is knocked forward off of a player’s body in any way other than a kick. At the knock-on level, you can cover the cost of one new rugby ball!
A line-out occurs when the ball goes out-of-bounds. Two lifters on each team will lift a jumper into the air to catch the ball, which is then passed to the scrumhalf. At the Line-Out Level, you can cover the cost of one member's registration fees.
A scrum is one way to restart play after a minor infringement. Both teams’ forwards bind up in three rows and then bind onto each other so that the front rows are interlocked. The scrumhalf throws the ball into the gap between the two front rows, and the hookers on both teams try to hook the ball back with their feet while the other forwards try to drive the opposing team away from the ball. At the Scum Level, you can cover the cost of one hotel room for a tournament in another state!