And it seems that 14 years old is also in the rebellious period, if you talk to him about this in a serious manner, and also use the tone of lecturing, he may not necessarily listen to it, and may even be against you
If you are parents who are friends, you should direct the topic of conversation to your son's school life more often, and understand your son while helping him solve his confusion and so on. The first thing that you need to do is to get to know your son and help him solve his problems
Note: The tone of your voice should not be very serious or harsh.