Okay, so my daughter was like that, from Kindergarten. A perfectionist.
Her Teacher even noticed, and spoke to us about it.
My daughter, even in Kinder, would cry... if something was not perfect enough etc.
We knew that about her. But the TEACHER also talked with her about it, to help her ease up on that.
My daughter is now 9, and is no longer like that and is not all anal and a perfectionist. BUT... she is still, a VERY hard worker, per school and the quality of her work. She always tries her best... and that, is good enough for her now. Because she knows she does "her" best. It is now, not just about a number score. She has matured and in her knowing herself.
And she is STILL a great student, who does WELL and the Teacher's recognize that, in her. It is her work ethos and attitude, as well.
We taught my daughter... that the WORK ethic, is important... it is not only about a numbered score.
Because, even people who have NO education... can be remarkably, successful.
Also, at certain ages, some kids are "perfectionist" like. But it is a phase.
But still, talk with your son. My kids' Teachers, never emphasize perfectionism... but that the child, try "their best..." etc.
It will take time, for your son to learn this.
Teach your son, that even Einstein... made mistakes and was NOT perfect.
EVEN brilliant proven Geniuses... are not, perfect.
Being perfect also does NOT determine... the ability of a person.
And being smart or not... does not determine... the ability of a person either.