I like in the UK, where School Prayer is not just allowed, it's required by law. Since the 1940's a "collective act of worship" has been required daily in all English & Welsh schools, and while schools vary in how they apply this, it is the norm. By default this is a Christian act, though followers of other religions and atheists may be choose not to attend with written parental consent (very few actually do in my experience), and in Schools with a high diversity of faith backgrounds the content can be multi-faith to reflect that. The government takes this seriously enough to last year prosecute a couple of schools for failure to comply as i recall.
Still, I grew up with prayers in my class first thing, then Assembly where we sang hymns and listened to the days announcements and a short talk, then after lunch paryers again, then prayers as we ended the day. My school was not very religious - this is State schools I'm talking about. I don't know how typical my experience was, but it was consistent over Primary Middle and Upper school, right from 5 to 16.
We of couse also have a legal responsibility to learn about Religion in class, also worth noting...
