Unit 9 (we went to the airport)
We use The simple past and the past continuous together to show that the past simple action happened in the middle of the past continuous action, while it was in progress
While Sara was washing the dishes, Dad got home.
Dad got home while Sara was washing the dishes.
(While) + (Past Continuous Tense) , (Simple Past Tense)
(Simple Past Tense) + (while) + (Past Continuous Tense)