The best way to put God back in the schools is to teach the kids that they aren't the "little angels" that they, their parents and teachers constantly lead them to believe they are. Place the moral onus on them to behave like decent human beings, sit down, shut up, and engage with the teacher to learn what is being taught. Also point out that many of them will fail, die young, go to jail, go nuts, fall into poverty, get or get someone pregnant out of wedlock, etc, etc, etc, just as every 'class' before them has done. And that they will likely become victims of the 'world' because of their own greed and stupidity long before any of them bring meaningful change to it.
That would be a good start.