Having potential is not the same as getting results.
Maybe he’s a visual thinker. Schools don’t fit well with all types. Calculus, for example, is not easy for many very creative people but our insistence on it blocks the system from meeting their needs. I loved calculus but it was useless in my professional engineering career. My visual side was the source of my problem solving and machine design successes.
Or you need glasses, or dyslexic, or a number of other things that impede learning.
Any number of reasons could account for the low mark.
No, he is not smart enough. Most of the kids in school have average or below average intelligence.
Then teach you answers some lessons.
I shoulda used that response when my dad told me this XD