I want A job but my parents won t allow me to.?

Yeah my description lives up to the title. So I am going to be 16 in a couple of weeks. I m getting ready to be a responsible young man and land a job somewhere but there is a wall that is blocking me. A wall called "Mom"! My mom says that I need to focus in school. I understaf where she is coming from but seriously im a high 80s type student. 87 avg usually. She says that I need to focus on studies and that she d rather have me moe lawns, or do yard work for neighbors. But that is not what I want to do. I ve done that before when I used to save for something, but I mean a real J-O-B. Like any entry level fast food job. Ok sure I get taxed the hell out of especially here in NY but seriously! I want to work hard for and to start buying my own things. I want to be independent. I understand that I need to do well with studies but I tried to tell my mom that I have alot of time. School runs from 8:00 to 2:40. I ll have plenty of time to work, study, and get good sleep. There are 24 hours in a day. I know I can do it. As far as my dad goes, he somewhat supports working. My sister works and he likes that. He might like the idea of me wanting a job but my mom is mostly what is stopping me. I told her that I can work just on week ends, but she didn t answer me after that. How do I convince my mom to let me work?