<p>The reason is that the Caltech intro courses are, with high probability, quite a bit more advanced than the courses you would like to substitute for them.</p>
<p>Indeed, most Caltech core science courses assume that you already have the corresponding AP course under your belt (or an equivalent college intro course); most students do. Acing the AP chem, physics or calculus exams does not correspond to knowing the content of Chem 1, Phys 1, or Math 1 (and in the last case doesn’t even come close). Most state school courses don’t provide really good substitutes for these either.</p>
<p>You can take the Caltech placement exams, and that’s really the only way to determine if you know the equivalent stuff. The main exception is that for physics, if you do well on the mechanics placement (Phys 1a) exam, sometimes the professors will accept a transcript from a (good) course at a university on the Phys 1bc material in lieu of the exam.</p>