Composing Music

Daddy: "Do you want to do a new song for your piano lesson today?"
Samuel: "Yes."
Daddy: [thinks quickly to try to pick a song they haven't done]
Samuel: "Let's do this one: <sings a new song>"

I didn't record his initial singing, so I'm sure what we ended up with is only approximate. But here's a recording of us both playing (with only me singing) his new song: Mary Had A Cow