I've always thought of Alma Mater meaning university...
Nobody from my high school (Osseo).
In the modern language, it is often any school, college, or university at which one has studied and, usually, from which one has graduated.[2]
I looked up the definition before commenting.
In my past experiences, usually when people ask your Alma Mater, they're referring to college.
Uhhhhh i think the best player that went to Roseville was Sertich.