I ve seen some coaches yelling at the referees. Is this allowed?
No. It is never allowed. Those coaches should be warned with a yellow card. A second yellow card is the equivalent of a red card. A red card means the coach (or player) must leave the game and the vicinity of the field. There are several problems with this behavior. It undermines the referees. It discourages referees from being referees. We are already in need of refs and we don t want to lose more people. It sets a bad example for the players. It encourages the parents to criticize the referees. In the worst cases, it can lead to physical confrontations between spectators from opposing teams.