An independent clause is a group of words that contains a subject and a verb and expresses a complete thought. It can stand alone as a sentence. In the sentence you provided, the independent clause is "make sure you do your homework." This clause has a subject ("you") and a verb ("make sure"), and it conveys a complete idea. The part of the sentence that begins with "When you get home from school" is a dependent clause because it cannot stand alone as a sentence; it requires additional information to form a complete thought.
