what's a TA

Teachers assistant

Definitely can be changed

she might have to prove that she knows the concepts as well?

I've never known a TA that wasn't a grad student. Not only would a grad student not need to prove they know undergrad content, but they have to be selected to be a TA.

My stats professor this semester selected students from the class to be his TAs. Some universities allow them to be undergrads.

You can be a TA of any class after you've taken it and the teacher accepts your app.

Could also be a high school class. Very common to have a TA for a class that's taking it as well

This. My high-school had student TAs. The fact that the TA erased OP's name makes it seem very unlikely that it is a college or university, since most professors require typed papers/homework (at least in my experience).

Teaching assistant

Ah, alright. Thanks!

Teacher's Assistant.

All they have to do is compare handwriting. A hand writing analysis would be the end of that TA and justified expulsion if this is a university class. Although, it's a slight ydi since OP didn't bother to check their grade throughout the semester. This OR everyone is misinterpreting this when the TA isn't actually a TA and OP just got duped real hard.

Yeah, this. I think bringing it to the teacher first could be risky as you don't know what's happening. I would at least start things with the dean or honor council or whatever your school has OP. That's seriously fucked up. Hopefully your handwriting and notes prove it's yours. Bring all your rough drafts of your papers with you to back up your claim.

if possible it might help to type or write all papers in pen...

This is the biggest thing that is confusing. I have yet to know of any science class that doesn't want you to use pen. Especially for things in regards to a lab notebook, tests, notes. I guess OP's professor wasn't really finicky with which writing utensil to use. This really does need a follow-up to make it a bit more believable. The biggest thing that makes this unbelievable is that the TA is taking the class as well. That makes zero sense. Another thing that doesn't make sense is that OP didn't catch this a lot earlier on in the semester. Either OP is really bad at keeping up with their grades, or again this possibly is fake. It wasn't a bad read though. Gave me a good chuckle.

If the work being collected is multiple choice on a scantron, OP would have had to have completed it in pencil.

Depends on the teachers preferences. The majority of mine like to get the assignments in electronic form on a USB key, so a TA could easily just open it and modify the paper. Plus, if you're unlucky, you might end up with a teacher who just uploads all the grades at the end of the semester. I'll agree it's possible it's all made up, but it could just be that the TA took credit for more major assignments that were graded later in the semester, leaving OP unawares of what was going on.

Don't you still write your name in pen on scantrons?

Anybody downvoting this guy has yet to read the title/name of this FML

And I didn't catch it until after I wrote my post. Then, it seemed like a great coincidence!