I retired last May after 37 years in education, most of it in special education. The students I worked with had learning and behavior disorders. I gained a reputation as a problem teacher because I challenged the regular class teachers who would not make the required modifications. Many people get into teaching for the wrong reasons and don't have the understanding or patients needed to work with students who don't fit into the "box" that education expects students to fit into.
I went through this with my younger daughter and she's already going through it with her 4 year old. He doesn't have ADHD, that I can tell, but he's very smart and is also bored with school. He knew all his letters and numbers 1-10 this time last year and he hasn't gone any further and this preschool/daycare. We're all suspecting he may have obsessive
compulsive disorder because he gets pretty upset when things aren't in the routine he's used to. He's just like his mom was, very smart but learns in a different style.
Personally, I'm glad I am out of education now.