There are lots of great vocalists, and most of them can't hold a candle compared to the late Sam Cooke. The record that gets the most plays around my house is definitely the aptly titled Portrait of a Legend. Most of his songs are ingrained in our brains without even realizing how or when it happened. "You Send Me", "Bring It On Home", "Cupid", "A Change is Gonna Come", the list is never-ending. Sadly the greatness was short lived as Cooke died in a pretty bizarre situation at the young age of 33. Thankfully he had been working hard before that and left us with quite a catalog.
A good primer for kids to start getting them familiar with both Cooke and school, is the hit "(What A) Wonderful World". As parents, the song can be emphasized in the sense that the one thing I do know "is that I love you." Of course the sentiments for school are even more obvious as the lyrics are basically a who's who of school subjects. He even sings about a slide rule for gosh sakes, have fun explaining what that is to the kids. The simpleness of the song's lyrics and the amazing smoothness with which Cooke handles the vocals also equates to a great singalong for the kids. You'll be pretty proud when your toddler is talking about trigonometry.
Of course the original, below, is the cat's meow, but for the sake of variety here is a link to the Jerry Garcia Band covering the tune in Richmond, Virginia in 1993. Presumably Jerry used a slide rule in his day.
Here is a lyric sheet to use to have the kids singalong. As always anything you want to reuse I'd recommend laminating.