Can a child of 5 yrs be asked to leave the school?

Dear Sir / Madam, I would like to seek a help from this forum to guide me if I could lodge a legal complaint. My child is 5 years old and studying in Prep class in a reputed school of Jaipur city. We were informed by the school that they will not be able to let my child continue in the same school from next standard i.e. class 1. The reason they have given that there will be only one teacher in the class, as our child is hyperactive hence they will not be able to handle him. They do not have capable enough staff to handle him. They agreed that the the child is very sharp and excellent in academics. As per them they have managed till the Prep class and beyond this it will not be possible for the school. My kid is studying there for last 4 years and we were informed about his naughtiness only in the month of October 2014. We were asked to consult a doctor as they suspect the kid to be a special child, which we did and as per the doctor the kid is having ADHD but he is absolutely a normal child. We informed the school about the same and also informed them that the doctor has prescribed a medicine and mentioned that it will take at least a year for the kid to calm down. We requested the school to call us up or leave a note on the kid's class diary so that we can counsel our son. In between they called us once that we are not able to handle your kid and please take him back. Other than this once incident there is nothing that we informed to us since October 2014. We would like to put it across to the forum that we both husband and wife are working and our kid stays for the whole day with my mother in law, who is 60+ and having a severe problem with knee and my kid is absolutely manageable at home. Would also like to inform to the forum that for first two years he had been participating in all the activities, but for last two years he had been kept away form all the activities, be it sport or cultural. Even we were asked not to send to the venue as he may create problem. Today on 20th January we have been called up in the school and the principal had given her verdict that they will not let my child to continue from Class 1. Requesting the forum to let me know if there is any legal way that we can drag the school management to court for harassing the child and us.