Last week a church group blessed a public school in Columbus, Ohio. They did it from the outside which is open to the public. The principal watched from her nearby yard but did not participate or comment. In fact, no school officials appear to have been involved.
So, of course the ACLU tried to stop it. As I have complained before, they are not about the separation of church and state. They are about suppression of all public demonstrations of Christianity.
Since no government officials were involved, this was entirely a private act. People from other religions are also able to bless the school if they feel the need.
If the ACLU had gotten their way, government officials would have interfered in a group practicing their religion. I have a hard time seeing how that passes constitutional muster.