Songwriting

My poetry students were keen to learn songwriting. Around 15 years ago I wrote about eight songs for a rock musical - I wrote the lyrics, a composer wrote the music. Neither of us had done it before. He wrote a lot of music for instruments only, especially keyboards and pianos. We muddled along, created some awful songs and then gradually got the hang of it. By the last song, I was pretty happy with the result.
How on earth do you teach that muddling process to students? So I took myself off to a songwriting workshop that happened to pop up just when I needed it. It confirmed what I originally did all those years ago - it's about playing around, experimenting, trying things out until you find what works for you.
Great. And how do I teach that? Especially after finding out that only two people in the whole class could read music, none can write it in any form. So I spent ages choosing examples of classics for them to listen to, in order to look at how the songs are constructed, how the music figures in, what is a riff, what is a bridge, etc.
Well, either they're getting better at faking "blank and bored" or very little I said connected.
I am left wondering whether they thought I was going to give them a magic formula of some kind. After 8 months of poetry with me ... some chance.
Next week they have to bring in a song they like, with lyrics printed out, so we can discuss the writing process further. Then they're going to have to put their money where their mouths are (yes, we did talk about cliches too) and write something.