Title plss

I just remember some scenes like they're in a class and the teacher was asking how to kill goblin or some other type of monster and the mc's answer has angered the teacher and she/he tried or let the mc battle the monster and he did killed it the way he answer like punch it ( the monster's had a hard skin so it can't be killed like a single punch) but he proved his answers are right mulple times, every question he demonstrate it killing diff monsters with easy and basic attacks just like how the answer he was written by.