Elementary school is the most important phase of any child’s life. Sadly, many school teachers unknowingly destroy the unique capabilities of their pupils just because they aren’t well-versed in that subject to understand that different approach. Here is the famous example of a recent 3rd-grade test sheet in which a student got his points deducted for his multiplication problem 5 x 3=15. He interpreted it as 5+5+5 which is completely okay, but the teacher for some reason had taught and maybe believed herself that the latter number in any multiplication needs to be used rather than the first one. This shows the mathematical shortsightedness of the person who is supposed to be teaching this subject.
Now the poor student would get confused because according to the teacher, tweaking “her rules” of maths doesn’t work. The same thing can be seen in the question below as he had to make an array of 4 x 6 = 24 and he again used the same technique of using the first number as a base. The teacher deducted marks again.
This image of the paper was uploaded on Imgur and Reddit where this particular teacher received a lot of flak from the users because of this by-the-book checking method. You can see the thread here. I believe there is nothing worse than insisting a child is wrong when the poor fellow is right.