Exposure to death and the reality of it is fine. But they could have picked someone who wasn't from their school district.
Agreed that it's somewhat morbid to consider that one of their classmates was on the table.
HOWEVER....As long as they were informed of what they were about to see and they knew and understood that the deceased was someone that they might've known, they (the parents) don't have a leg to stand on.
I can't imagine in this day and age of a parent having to sign a freaking note for a kid to get an aspirin at school that the parents didn't know about this autopsy AND signed off on it.
Quitcherbitchin' Mom & Dad. WTF difference does it make if it's a middle school student or a high school student? Anatomy looks the same. Dead is dead.