Khan Academy is really useful. You can pick your grade level and what course you're taking. It has all subjects and even programming. You could also try asking you're teacher if she offers tutoring in the mornings or after school so you could come and practice. Try reading more books too. It could be any type of book, it doesn't have to be about math or anything it could be a chapter book or whatever. It helps with essay writing and vocabulary words. For science I recommend you watch Amoeba Sisters or ASAPScience. Plus watch documentaries that you enjoy watching. It doesn't technically mean studying, but it teaches you during your free time.
