More examples about simple past versus past continuous

Last night, Peter _____ (work) in the studio, when suddenly he _____ (hear) a scream.

Two simultaneous actions in the past, first he was ... yes, you're right working in the studio and after that he ..., right again, he heard a scream. So the sentence should be completed as follows:

Last night was working in the studio, when he heard a scream.

My parents and I _____ (travel) because it _____ (rain).

Two simultaneous actions in the past, first ... it was raining, and my parents and I ... traveled, the answer should be:

My parents and I traveled because it was raining.

Although in this case a more logical sentence would be:

My parents and I didn't travel because it was raining.