Tips on focusing in class?

School work is usually easy for me, but my report card came in the mail and I got a C in math for not taking any notes. I know, I might as well give up on going to Harvard and register with the welfare office. Insulting me isn't necessary as I'm already disgusted with myself for it. My mom has ADHD so she might have some Ritalin in her medicine cabinet. I'll look later. I start the 8th grade in a few months. Please help, I'm totally panicking.