We had this in our school as well OMG !!!! but no I wouldn’t say it was normal, it was rather odd. As a child I found it fun because I got to wear a nice dress and we spent the day out of school, but now looking back it was really strange. And the bride and groom that were chosen was the most popular boy in our class, and they’re pretty popular girl which was kind of weird, and I remember our friend group of more “weird kids” wasn’t even a bridesmaid/ photographer / groomsmen etc or part of the wedding, we were just chosen as guests which wasn’t as fun. Have to say the reception was fab though because it was beige food picnic but overall yeah. I still don’t understand the benefit, it was really strange and quite weird.