I liked movable-do solfège when I was in my two-year theory core... with a little bit of practice (only 15-30 minutes) I found the syllables made sense.
Their lesson on Major And Minor keys will tell you all about major and minor keys and scales, as well as a system called Solfege.
Origin
French.
Definition of solfège in US English:
solfège
nounsälˈfeZH
Music
1Solmization.
1.1An exercise in singing using solmization syllables.
2The study of singing and musicianship using solmization syllables.