Why do smart kids sometimes do badly in school

Teacher: “ If I tell you 3x5 = 5 + 5 + 5 and 4x7 = 7 + 7 + 7 + 7 , do you understand what x means?

You do? Good for you, but we are going to do 50 more, not everyone got it as fast as you did.

20 minutes later:

Teacher: Wake up and tell me what is 36/4!

Kid: What does / mean ?

Teacher: This kid won’t go anywhere…

What happened? The kid understood the first thing faster than others, so he got bored when the teacher kept explaining the same thing. He stopped listening and started doing something else, but then the teacher told something new. The kid sees something appeared out of nowhere, he just needs to know what it is, but it’s too late, he’s but another bad kid.

Then, this situation happens during exams, and the student spends a lot of the test thinking “What the hell are those things?” and they fail the exam. Then they look for explanations, understands them, and is now better than most of those who did well during the test. But the school doesn’t care, a lot of them are good enough.

I chose a very simple example to explain how it feels the best as I could. I’m not complaining concerning education, it’s far from being a simple issue.