This unit covers the past progressive or past continuous tense. This tense is used to show an activity happening in the past that is interrupted by another action or event or to indicate simultaneity of past events or actions.
For example: "I was listening to a podcast when I heard a loud crash."
"We were walking home as the sun began to set."
The past progressive is used when referring to a moment in the past, during which something else was happening. In other words, something that started before and ended after a specific time in the past. To form the past progressive, we use a noun or personal pronoun + was/were + verb + ing.
I arrived at the concert around 8 pm. The band was already playing. (The band started playing before, and continued playing after I arrived.)
She called me last night, but I was already sleeping. (I fell asleep before she called, and was asleep after she called.)
We wanted to go to the flea market yesterday, but they were already packing up.