It definitely feels wrong. Unless they have a very good reason it's not necessary.

I mean, sure seems like this is just ragebait and the “school” is more likely a university health center asking an optional question on a new patient form.

Dried blood looks more like a chocolate stain. I’m not sure they would get the point.

Florida schools will no longer ask student-athletes to share their menstrual histories in order to play high school sports

Wow, fuck that.

I mean, that has already been answered 12 hours before your comment. But if we really didn't know the context, it's not an unreasonable assumption that it's for research purposes; handing out questionnaires in school is by far the easiest (and thus cheapest) ways to gather data (anonymous or otherwise) on teenagers.