Might be useful to know what age they are,so as to choose something suitable? Looking ahead a bit, but giving them time to learn it, if they are old enough to understand a bit about relationships, "Twas on one April Morning"? No chorus, but they could repeat the last line of each verse as a refrain: and most people sing the first verse again at the end.
For March, you could do "Lakes of Ponchartrain" - Ok, it's American, but they might like the alligators!