I cant concentrate on doing homework and i cant sit still long enough to do it. Please help!!!!?

Try doing more involved studying, make flashcards or make quizes and tests and test yourself rather than just reading out of the book. Try to talk to your doctor if it becomes an issue, he may prescribe you a medication for it which could help. Just make sure you are in a quiet environment with a lot of time, take breaks in between and remove anything that could distract you like a cell phone or computer.