Make sure you know your modes! A normal C major scale would just be played C to C, known as an Ionian mode. D to D would be a Dorian mode and so on. Medieval music didn't really have such a thing as the major and minor scales, instead they just played around with this one scale using different tonic notes. The Aeolian (A to A) is the closest to the minor scale, and in late Renaissance music you'll start to hear the minor scale established. There's a book called Theory of Harmony by Arnold Schoenberg, that discusses why the notes of the major scale were chosen and briefly why the minor scale came about. Modal music will be great to learn about as it's returned both in improvisational jazz and metal (phrygian and locrian modes).
Sorry, I ramble, but maybe this was interesting to you. The stuff you study will be very rule-based and diatonic, and maybe to an extent decided by superstition. For instance, the diminished fifth interval was avoided because the church decided it was evil, or the "devil's interval"!
Have fun on the course!