Prayer in school is legal, students already have the right to pray voluntarily, as long as it's not disruptive. Fact is the public has a right to pray or not to pray and that right is protected under the 1st Amendment. If you don't like it, then seek to change it. But why should a few such as yourself dictate when, where or how the rest of society, which is the majority of Americans, can exercise their religious freedom?
Prayer in public school is legal, provided it is not mandated, part of the regular, school routine or disruptive. In other words, students can voluntarily pray in public school on an individual (or group) basis. The public has a right to pray or not to pray, and that right is protected by the First Amendment.
What you are doing here is what so many do - thinking that the Free Exercise clause trumps the Establishment clause, and it doesn't. People can do whatever they desire in the form of religious observance on a PRIVATE or INDIVIDUAL basis. That right is protected from GOVERNMENTAL interference by the Free Exercise clause.
When, however, an agent of the GOVERNMENT, such as a public school teacher or a public school itself, attempts to force religious observance on students, then the Establishment clause steps in and prevents it.
See the difference?