Possible learning disorder ?
 

So.... i have a little sister she is 15 she has been having a hard time with school and i have been noticing her struggling with Number and some Words. She has been having hard times understanding things so i dunno if this could be a possible learning disorder of some sort...

my sister went from a's to c's and struggled until our mom put her back in line, at that age little girls have a harder time with school than with personal life, is she having issues with things outside of school and did she have this issue before?

No not really she has always have had trouble learning and stuff

Well different people learn at different pace and different style (such as hands on learning, audio/visual learn,etc.) , so have you though of a Tudor or helping her? And be careful when the teacher tell your parents that she needs meds to help her learn they don't do anything other than it get her high.

I prefer a helping hand with those subjects after school like a Tudor or help her with homework.

The only way to truly tell is she needs to be tested. Public schools are required to provide that. Your parents will have to go to the learning center of the school and demand it.

I've dyslexia and it was noticeable since I started learning to read. I had an awful time with reading and vocalizing my thoughts or writing them.

It could be possible, and as Lioshika said the only way to know for sure is to get her tested, but there could be other problems. She might be having trouble concentrating due to social issues like another had said, or just concentration problems in general.