Government laws

Assalamualaikum. How are you?I wanted to ask you a question which seriously is worrying me a lot. I am having continious thoughts about that. My question is: The country in which I reside in does not permit a school teacher to give private tuitions to the student of the same class because of reasons such as favouritism.I am really confused about this. I dont think my teacher would ever simply favour giving more marks to me than others. And to be honest, I find his teaching the best till now. There are 3 other students besides me who are also attending his private classes. I told my mother regarding this but she looks helpless and says we are not doing any kind of cheating or so and so its fine. But I am very scared that I may be committing a sin.So what is your take in this? Is this sinful?If yes, then can I quit going to these classes after the month time period gets over. Moreover I dont feel good to leave his tuition for the fear that I may make him feel bad. Please help me with this.