We use the worship chorus, Father I Adore You, to practice two basic harmonic progressions: (1) I – ii – V – I; (2) I – IV – V – I. These progressions occur frequently in worship choruses and hymns. Then we practice seven different stylings involving these progressions.
We use language that is commonly accepted in both popular and classical music circles. Popular/Commercial musicians use pop symbols whereas classical musicians are taught to think in terms of roman numerals. You will need be to be familiar with both.