newspapers.com for Annie Beck, 1880 to 1903, San Francisco.
reference to Annie (Senior)'s death in 1897, but you have that.
also, for schools:
https://www.newspapers.com/newspage/27532488/San Francisco Chronicle
Issue Date: Friday, June 17, 1887
Page: 7
a listing for
Annie Beck, seventh grade
possibly at the Whittier Primary School
Miss N. A. Maloney, Teacher
Note find someone with a subscription. I am only trying to make sense out of an OCR scan and might be wrong.
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And this doc talks about SF schools during the fiscal year ending June 30, 1886,
listing for
Whittier Primary School - Harrison between 4th and 5th < - would agree with Clara St location on the map
and says the Girl's HS location was on the north side of Bush Street between Hyde and Larkin
https://library.sfgenealogy.org/directory/san-francisco-county-directory/1887/1887_49.pdf----
Annie Junior wouldn't have entered high school until about age 13 or 14, unless things were different back then. I was 13.
7th grade at age 11 would be about right, but a little young.
edited to add: Or it might have been promotion /to/ 7th grade which would fit a little better. The article was about promotions, I think.