You will also undoubtedly hear about writing to the HOOK. In other words, the HOOK is the key element of the message of the song and so all other elements relate to or refer to the HOOK.
In writing for very young actors, sometimes all you can do is build on the HOOK. You do not have time to write verses and choruses, let alone a bridge. You have to write a singable, memorable, catchy tune using the HOOK in less than one minute!
So, I had to come up with a show for them. In less than eight weeks, our only option was to do an in-class mini-musical. What exactly do you do with one boy and seven girls? Well, fortunately the boy was larger than most of the girls and he could sing and dance. So, over the weekend, I wrote three songs and a script that could be learned very quickly.
These songs are all built around the main message (HOOK). I also needed some quote or bullet point to serve as the Character Value. I remembered a quote by John Maxwell "You can play now and pay later or pay now and play later. Either way you'll have to pay." That worked perfectly for the finale message song.
So, if you analyze songs from musicals for young children, you will likely discover that they have no verses, but probably have something that sounds like a chorus and possibly a contrasting big finish. Most are simple 2 section (call it AB form) songs.
Check out the songs from "The Ants and the Grasshopper." They are short and to the point!