[Plummz]

It is rather odd that Stanley Ann is dressed differntly than the other girls in the picture. The only reason I could think of (for a legit picture) is that this is the picture of an athletic team, say the girls' tennis club, and Ann was the team's "manager" rather than an athlete.

I don't see this as being a cropped portion of a full "class picture" because there are only girls in the photo. A class picture would have all the boys and girls mixed in together.

[Fred Nerks]

I’m an Australian, I do not know all of your customs, but one freeper did tell me there is/was an occasion during high school, where all the girls of a grade will/did pose in their high school sweaters, and all hold the same pose as the photograph is taken.
She’s a ‘woman of a certain age’ who maintains she has a similar grade photograph in her own album.

To her eye, there are girls missing on the left of the image, there were less girls in the back row than in the front, SAD is an addition/insertion - and if she (freeper) had turned up for that photograph session without her sweater, she would not have been in the photograph she has in her album.