The father learned that he is a crummy tutor. Time to send the kid to a professional.
Would the kid have scored worse, better, or the same without the father’s tutoring?
We had one daughter that varied a lot depending on her teachers. Some years the teachers were good and she “got it” in math. Other years we had to send her to professional tutors. And even there, they would have to match her up with the right tutor. We taught them at home with some stuff (like memorizing the addition and times tables - which was against the school district rules to be taught!), but as they got older it was too much.
And those years she would be in her math class and explaining it to all of the other kids that didn’t “get it” due to the lousy teacher.
One teacher never even taught!! She would play a video of the lesson and then hand out the worksheet. She would sit at her desk browsing and shopping on the computer! Wouldn’t even help a kid if they asked.
The damage those types of teachers do to our kids, and in effect - our country, is treason.
I understand. Kid wanted to humiliate father. Can’t fix stupid, it’s genetic sometimes, or environment, still can’t fix it from the outside.