<p>Here is the important thing: Don’t stress about it. There are plenty of things that you can reasonably worry about regarding any university application, a grade that is already on your transcript is definitely not one of them. For the record, I got in early to MIT with several B’s on my HS transcript. </p>
<p>For example, one was in trig, and to be fair, I was lucky to get the B. I never really understood trig, when I did it in HS. I simply could not see the point of memorising that sin(2a) = 2 sin(a)cos(a), and so, largely I didn’t do it. It wasn’t helped by the fact that I had a trig teacher who could not explain why we would ever need these things. So I struggled to bring myself to remember them. Not long after that, I reached calculus and then I could really see the value of my trig, and when I started looking at computer graphics and the linear algebra involved in the projection of a 3 dimensional object onto a 2 dimensional surface, well then my trig got really, really good. But I had a deficiency notice sent home to my parents by my trigonometry teacher. At the time that that notice went home, I was president of my high school math club, captain of the math team, I had done well in most of the national math competitions, and I had a deficiency notice sent home in a math course. That was embarrassing at best.</p>
<p>But the thing is, I did not fret about it. I did not dwell on it. I certainly did not write to MIT and try to explain it. I figured that I did not want to attend any school for which that B was a determining factor. One of my LoR’s was from the faculty advisor to the math team. I got into MIT early, and I wasn’t in the top 5% of my HS by GPA. What I did have was plenty of evidence to show what else I had done with my time, and what impact I had had on my school environment. I was able to show how I had made my choices, and what they meant. That is what got ME into MIT. Your mileage may vary.</p>
<p>I have now been an EC for some years, and I have interviewed a huge variety of kids, many of whom had radically different things that had demonstrated why they should be offered a place in an MIT class. There is no one path, no one rule, no one guideline to follow. But I cannot think offhand of anyone who was admitted because they could show that they did well in class. </p>
<p>Just as there is no hard and fast way to show that you are passionate about (for example) robotics, there is no mathematically calculable method of showing that you are academically qualified. But being academically qualified is necessary but not sufficient for MIT admission.</p>