I should also add something:

Just because you have trouble concentrating in school or memorizing study materials doesn't make you stupid.

It is more common than you think for people with high IQs to do poorly in certain subjects in school because they are either bored by them or don't consider a point to studying them because they won't actually use them in the real world. Take my personality type as an example: INTJ; the rarest personality type out of the 16 Meyers Briggs personality types and the most knowledge seeking one as well with many INTJ people having IQs over 120, yet if you go to an INTJ forum, you will find that many of them made average grades in certain subjects because they found the study material boring or didn't see the point of knowing it and would rather devote their time to learning things that interests or benefits them.

I think that an issue with higher education in general is that they want people to study so many things that serve no real point outside of a few career paths. Take advanced math for instance; math above high school algebra is not used at all in the real world UNLESS you are choosing a career path that requires it such as becoming a computer programmer, a mathematician, or a physicist for instance; if you aren't doing any of those careers than there is absolutely nothing wrong with not being good at math. The same can be said for certain parts of history or science although I won't get into too much detail and what subjects are needed where as this isn't the point of this thread.

So just because you aren't good at learning certain things doesn't mean that you are stupid or inadequate by any means; there is likely something that you are good at somewhere such as art or music or even helping people for instance that you could be well above average in, therefore, you should seek to learn more about yourself rather than what people tell you and operate to your strengths and you should be fine