That's what I came up with.
1. First, I played this wonderful video for them (without showing the lines) and asked to write down sentences with modal verbs they can hear. The video is a compillation of various song extracts containing modals.
2. Next, we checked what lines they had. They were supposed to have these:
May it be.
We might as well be strangers.
We might as well be living in another time.
I just can't get you out of my head.
I know I can be what I wanna be.
You mustn't sigh and you mustn't cry.
The show must go on.
My makeup may be flaking but my smile still stays on.
It must be love.
You've got to let me know, should I stay or should I go.
It's also a good idea to elicit students' answers on what modals express in each sentence (e.g. ability, permission, obligation etc.)
3. Finally, I asked them to write a short paragraph that could be a beginning or an end of a story, or some part of it, like a monologue of a character etc. The requirement was to incorporate one of the lines they'd written down.
We had lots of fun when they were reading their pieces! There were extracts from romantic novels, drama, philosophical essays, you name it. It was quite a productive outcome I didn't even expect, especially that this idea was born very much on the spot ))