You tell him (her) first and ask him if he understands. If he did, let him tell you again. In the process of speaking, you can find problems, such as whether he really knows or misunderstood. If you don't understand, ask him step by step which step you don't understand (or let him tell you).

It's normal for them to be inattentive at their age, especially when his grades are not very good. lz doesn't need to worry about this. Only if he can really do these problems will he feel happy. For example, when a classmate asks him how to do one of the questions or the teacher asks him, he will praise him. At this time, he will gradually fall in love with learning and enter a virtuous circle.

Children are at the age of play, so it is not easy for them to study with peace of mind. Come on lz ~ ~