I would advise all students to continue to pay special attention to the Oddballs, Bb Major and B Major. My students learn Db, Eb, Gb and Ab Major rather quickly but often continue to miss Bb Major and B Major.
Note: More advanced students will understand that there are two ways to write any major triad when both the bottom key (the root) and the top one are black keys. I have chosen to write all of them using flats, but sharps are also possible. I will cover the “sharp problem” next, as a separate entry, for those who are interested.