Start and stop the clock on every time out, foul, out of bounds and violation. You will have to have your hand on the clock to start and stop the clock at the sound of the referee's whistle. You will also have to change the score with every made field goal, 3-point field goal and free throw.
Keep track of every player who is in the game. Any time a player comes into the game, he must report to you. Players can't go in the game until you let the referee know that the player has reported correctly. If a player goes into the game without reporting, you must let the referee know.
Record all player and team fouls. Players can accumulate four or five personal fouls before they are ejected. Depending on the level of play -- high school, college or professional -- players foul out of the game on their fifth or sixth foul. If a player fouls out, you must call the referee over to let him know that the player has fouled out and is no longer eligible.
Keep track of all team fouls. When a team has exceeded a certain number of fouls -- the number varies between high school, college and professional levels -- the opposing team goes in the bonus and may receive extra free throws. You have to let the referee know when this occurs.
Operate the clock as honestly as possible in game-ending situations when involved in close games. You may be a teacher at the host high school, but you cannot show any favoritism by starting or stopping the clock an instant or two late. Operate the clock with integrity at all times.