Not necessarily so I believe it's more of effort than intelligence. Students with good grades sometimes fail aptitude tests whiles those with average grades pass. It has got to do with discipline and finding an interest. Intelligence is too big a word to be classified as good grades only. Good grades are more often than not borrowed knowledge. The thing is that, good grades only cannot depict intelligence. You need more than passing written exams to succeed in life. Trust me, I was top of my class in college, and i knew this girl in class who graduated with only a pass. You need to see her speak or give a presentation and you would realise she has great language aptitude, which is a kind of intelligence i believe.