Yes, organized prayer before public school sports is acceptable, because it is as much historical and cultural as it is religious. A person who does not believe in prayer does not have to pray along. If most people want to pray, they should have the option. This is what has been traditionally done for years, it shouldn't be stopped because of a few loud dissidents.
As an Atheist I'm not of the opinion that prayer is necessary AT ALL. That being said Pre-game prayer in public schols before sporting events is acceptable until there is a majority decision that it is not. There is a minority of atheists in communities for the most part. If there is not a majority present who dissaprove of these religious demonstrations then there is no issue. Only when it is found that a majority of atheists outnumber religious people should organized prayer be done away with.
So my daughter plays on her schools soccer team. She does not feel comfortable with the Christian prayer that is done before each game. She is cast as a none team player by her teammates and the coaches. So when I here the proponents of prayer say just don't participate with the prayer fail to recognize the stigma that goes along with not participating,
As stated by the Establishment Clause of the 1st Amendment of the US Constitution: "Congress shall make no law respecting an establishment of religion..."
Organized prayer within a secular public school clearly violates this. Individual students may pray as they wish, but the school may not sponsor such an activity, nor require it.