Foundations of the first aorist (perfective/punctiliar aspect; the snapshot view of past action), the -σα tense formative that marks the first aorist, the stem-vowel contraction rules for stop consonants (labial+σ→ψ, velar+σ→ξ, dental drops before σ), the Step 1/2/3 derivation of ἔλυσα (active) and ἐλυσάμην (middle), the side-by-side imperfect-vs-aorist comparison, a first vs second aorist preview, the parsing workflow for any first-aorist form, and translation practice covering all six person/numbers (active and middle) on Lesson 15 vocabulary verbs with stop-contracted aorists. Unlock each subtopic by scoring at least 90% on its mastery check.