This document provides a lesson on forming sentences in the past tense in Korean. It explains that the past tense follows a similar format to the present tense, removing the "다" ending and adding an appropriate ending based on the last vowel of the verb. Some example conjugations are provided like "가다" to "갔어요" for "to go" and "to went". The lesson emphasizes that the past tense follows the same rules as the present tense in terms of vowel or consonant endings. It concludes by recapping the different tenses learned so far.