My high school experience in handwriting analysis was not from a class in same, but was from TAing a geometry class where people forgot to put their names on their homework. I was generally able to match up paper with student by looking at the roster of students missing their assignments, and matching the nameless assignment with past papers belonging to that student. I did go a little above and beyond what was strictly required.

Any skill that can be used for good can also be used for evil; I also at one point or another forged a friend's handwriting when "helping" with their math homework.