Forget what I might think, go by the video. I’m an Australian, I keep telling you, I have no idea what a frikken sophomore is.
To the best of my knowledge that high school commenced taking students in 1956.
And I’m certainly not responsible for that video content.
That's interesting. Even Wiki has the school opening in 1957 which is consistent with my memory for reasons outside the record here. I think they in fact opened in the fall of 57 for the 57-58 academic year. But the only admitted one or maybe two classes--the Junior (11th grade 57-58) class of 1959; and maybe the Sophomore (10th grade 57-58) class of 1960 of which Stanley was a member.
But that would be consistent with your thesis if Stanley got in as a tenth grader (sophomore) in the fall of 57; would have had her there two years, sophomore and junior; and then she went to Chicago to work as an Au Pair and finish her High School there.
I believe it goes like this:
Freshman = 9th Grade
Sophomore = 10th Grade
Junior = 11th Grade
Senior = 12th Grade