Do you need to teach past continuous and is looking for something simple that requires no preparation and engages students? Maybe you could try this digital task out.
Aim - Sentence level practice of past continuous and simple past
Devices - Any device students have that records voice
Model the activity by playing a soundtrack and asking students to write a sentence to describe it. e.g. The boy was listening to music when the sound system broke. Separate the class in small groups and give them 10 minutes to think of a situation, write a sentence and record their soundtracks. Share students work and elicit what the sentences are.
The guy was listening to music when he crashed his car.
A couple was making out when the girl slapped the guy.
Two friends were talking when a cow mooed