We sang the song which "Guest: Imagine That" quotes. I was in first grade in 1941 and the song "Merry Merry Sunshine" was in a green cloth-covered hardback book of songs (Schirmer?). I recall:

Merry merry sunshine
Smiling in our room,
You have chased the shadows
And driven out the gloom.

Merry merry sunshine
When you're shining down
Smiling faces greet you;
Who could look at you and frown?