@stefano.massari, You did the right things. Help your son to understand better. Especially when you also enjoy your child's lessons. As if we are remembering the past when we were still in school. I am sure this will be a good example for children in learning. What he learns at school and then helped by parents at home will certainly make children more enthusiastic in learning.
I also believe this will be remembered by your son so that he will feel proud to have parents who are always ready to support his learning. This is a lesson in real life so that when he grows up he will be able to help other people, especially siblings or relatives.
Send my warm regard from indonesia for your son and family
@rrokhani.