This is a song from StoryBots: Learn to Read Collection 2. It's sung by Gabe Sokoloff.
Lyrics[]
When you grow bamboo, when a cow says moo, when a ghost says boo
You're hearing a double-O sound, it sounds like /uː/, /uː/, /uː/
But when you take a look from a recipe book 'cause you plan to cook
That's a different double-O sound, it sounds like /ʊ/, /ʊ/, /ʊ/
So let's review, you got /ʊ/ and you got /uː/
Now you know when you got double-O, it's likely one of those two
Now those are the two main double-O sounds, but there're a few more
Like the double-O sound that you hear in flood, or the one in floor
But most of the time those double-O sounds follow our usual rule
They go /ʊ/ like in hook, or /uː/ like in school!
So let's review, you got /ʊ/ and you got /uː/
Now you know when you got double-O, it's likely one of those two