The best way to ensure that all players get equal playing time is for the coach to set up a substitution grid and then have an assistant coach or team parent keep track of the time with a stopwatch (or, in the case of baseball and softball, keep track of the innings played).
Parents should ask the coach to put the playing schedule in a place where everyone can see it.
To ensure equal playing time, the coach should:
Prepare a detailed substitution pattern or "grid" before each game. Trying to keep track of how much each child has played during a game is next to impossible. It is much easier to do it the night before, when the coach can set up a balanced lineup with a mix of more and less experienced players. Writing out the lineup in advance also makes it easier to move players around so they can play different positions. Locking players into set positions for every game may increase the team's (coaches') chances of winning, but it can take the fun out of the game in a hurry!
Tell the players before the game starts when and what positions they are going to play. The coach should make sure that everyone gets to start an equal number of games.
Stick to the game plan, even if the team is losing. The coach should resist the temptation, in the heat of competition, to scrap the substitution grid if her team is losing to keep the "best" players in the game in order to try to win the game. Remember: Most kids, even at the middle school and high school level, play sports to have fun, not to win.
Equal playing time: a winning formula
Deciding on a substitution pattern in advance, and then following it during the game, creates a win-win situation for players, parents and the coach:
Players (except, perhaps, for the spoiled star who feels it is his or birthright to play the whole game) because they will have more fun, won't be resentful or jealous of each other, will play together more as a team, and be less selfish;
Parents (again, with the exception of those who feel their son or daughter is so much more talented that they are somehow "entitled" to more playing time at the expense of the players who at that point appear less skilled, or those who value winning above all else) because they will know that their kids are being treated fairly, so there won't be any need to confront the coach after the game or on the phone about a lack of playing time for their child; and
The Coach because (a) it will allow her to concentrate on watching the game instead of thinking about the next substitution, or worrying whether she has forgotten to give a particular player enough playing time; (b) the players on the sidelines won't be constantly pestering her, as the John Fogarty song says, to "put me in coach, I';m ready to play"; and (c) she won't be tempted to show favoritism towards her own child.