as salam alaikum
it may be difficult to teach Qur'an to a child on a personal level, especially by parents with whom the child already has a particular bond which is not a teacher-student one. Attending a madrasah may give the child good discipline and make him to confront with other kids in religious matters. Also, it would make him understand the relationship that must be kept between a teacher and his students, and to observe all etiquettes and manners in this regard. It is therefore advisable to bring children to a good madrasah with competent teachers to learn Qur'an, the fundamentals of religion and Islamic behavior.
With prayers for your success.