And equally the illegality of preventing prayer in a public school.

Can you give even a single example where a student has been prevented from
praying, as an individual, in a public school?

What is unconstitutional is for the teacher to lead the class in prayer as a
part of the school day, or to require that students recite a particular prayer
in unison.

Many schools even allow the formation of bible study groups that meet before or
after school. Outside of the normal school day, there isn't a problem with a
teacher serving as the advisor to such a group.

Most people who feel it's important for kids to pray in school and who believe
their kids will get a better education if everybody they are in school with
follows the same religion send their kids to private school. No problem. They
can pray for 45 minutes and study for 15 every hour, if they so choose.