I have read articles saying boredom in classroom cause anger. Dose any parent face the same situation?

On the day of math sheet incident, the teacher said to my son in front of me. "You need to learn how to be patient. I know you don't want to listen (the solution of math questions). Other kids' parents send them to school to learn, not to see you making funny faces. You need to learn how to study too. The things won't easy like this when you get older." Apparently the teacher knew he was bored but expected he sit through the class everyday.

I was not happy but didn't say anything because I did think ds was not respecting teacher.