Mrhillnc's quick comment on evolution is not very correct at all, but that was evidently not the point of the submission, so I will move on.

Students are absolutely allowed to pray at any time during any of their free time, there just isn't time set aside in which everyone is expected to pray, as there once was, because of course not everyone shares the specific superstition of prayer.

Anyone is allowed to pray, to meditate, to sleep, to write in a diary, to doodle on their skin, to masturbate in a bathroom stall -- whatever they wish to do during their free time provided that it is legal and does not disrupt students at work.

I agree with the implication that school occupies too much time in a child's life in proportion to the time they get to spend with their family or in solitude, but that is quite another topic.