I don't understand

Another thing is how old is she

Yup, but ig at some point it's meaningless to count...

It looks like they measure how they use their powers vs their actual powers. All of the powers in class f are being proven to be better than class a’s for this reason I think

Sounds right, but on the other side if it was purely about the use of the power then it's weird that theres no ranking or advancing system. It's just class A and then F, when it's proven that powers can be improved, and they are also super diverse. So the binary solution is kind of weird. Also they treat the kids with weak powers as the worst of the worst, when in reality they are just the normal kids with a quirk. I get the other kids from school or even teachers, but the whole society thinks like that?? It's weird that they are treated like trash when there no reason for it.
Anyway sorry for overanalyzing, ig sometimes thinking too much can ruin a series so now I will shut up.

I might be mistaken but I believe that there are other classes in between, and I believe that one of the class f students was formerly in class A. & don’t worry, I love analyzing series too. And it seems like powers is a newish thing to the world from what I’ve seen. I haven’t read the beginning in a while but there are regular non powered humans so I don’t understand why they would be treated like trash when they’re still more advanced then them.

As far as I know, there's no mention of other classes, they are not shown on any graphics or mentioned in the text, so it's like confusing too, because it would be kind of natural direction to go. If you divide students based on how powerful they are. But I think the biggest problem is the treatment of F class students, it's a focus point of the comic, and a fuel for development, but it kind of doesn't make sense T. T Like the behavior is not adequate, there's no reason to treat them that badly. I think it would make more sense if everyone or the majority of the population had their powers, then yeah the weaker power would be looked down on. But at the current state, it's kind of falling flat. To be honest, it would also make more sense if people excluded or ostracized the characters with powerful powers, because they could look dangerous or inhumane to them. For example if someone has anger issues but also has some bomb power, then I could easily imagine people around being scared and excluding them/ treating them with distance or malice. Anyway again sorry for yapping, just happy that someone will read what's bugging me. And yeah you're right about transferring from S to F class, I think two students have done that, so I guess groups are not as stagnant as I thought they were.