As we continue to dive deeper into real "music theory", we add Unit 9. Unit 9 introduces students to their first written analysis of chords using "the Romans." I build triads off of the scale degrees in C Major to start, and show students how and why we do Roman analysis. Just like everything else in music theory, this concept will be built upon later. So don't rush through anything, take time to use my examples and make your own!
I do teach Unit 9 while still practicing concepts from older units, like major scale writing, playing scales on the piano, and doing aural dictation (chords and intervals).