There are many advantages in working part-time while you are at school. Firstly, a part-time job offers you a chance to demonstrate your ability and to apply what you have learned in school. Secondly, a part-time job helps you become more independent of your family. Thirdly, the experience that you gain through part-time work may be of great help to your future career. Finally, a part-time job can broaden your social knowledge.
However, part-time job has some disadvantages. For example, you may lose time needed for rest and reviewing your lessons. For another, once doing part-time job, you are likely to be interested in earning money that you may not pay much attention to your study. As a result you may fail in your examination and affect your future as well.
In my opinion, you have to strike a balance between schooling and the job. As a student, acquiring more knowledge, especially book knowledge, is your essential task. If you have to do it for your tuition, you should not spend much time on it.