<p>I took intro physics junior year (AP wasn't offered, unfortunately) and performed well, had a solid A through the semester, etc. For the semester exam, the teacher gave us a timed group lab. I randomly ended up with two people who, to be objective, were only in the class to fulfill their physics graduation requirement and were completely lost in the subject. Long story short, I got a B on the exam, which pulled my semester grade down to an A-. Later that year, I got an 800 on the physics SAT II and independently prepared for the AP Physics B exam, on which I got a 5.</p>
<p>This year (senior) I'm doing an college level physics course (a slight step up from AP Physics C, material-wise), in which I'm looking at an A- because my high school schedule conflicts with the college schedule such that I've had to miss a few labs, which I can't make up.</p>
<p>I gather the adcom looks at physics grades to predict performance in the Caltech core, so I expect these grades could really detract from my application, even though I find the subject pretty easy.
How should I go about explaining why I have A-'s in what should be easy A classes, without making it sound like I'm giving excuses?</p>