Online school/classes?

Does anyone know a really good online class that you used to take or having your child take? I'm fifteen and I wanna start looking so I'll be prepared for whenever school starts back up again. I know you guys are probably wondering why isn't my mother doing this, but my mom takes very long to do things and I don't wanna wait last minute for her to be looking for some. I am doing a co-op also but I'm not taking enough classes, I honestly wanna take more classes cause I don't feel smart enough...I'm so bad at math and I wanna get better at it! I feel really stupid and it's kinda hard to continue life knowing that... :(

Thank you. ❤️