Fun old-time folk music, beautifully played. Babies react to the music, toddlers dance to the rhythm and mimic the more repetitive choruses, preschoolers start getting the jokes, giggling, and singing along. And most of this is true folk music, too, not folk-influenced acoustic pop. Chords, guitar tab, variant lyrics, and sometimes even full sheet music can be found free online or at the library for many of the songs, so if your family has a musical bent, you can adapt them and sing and play along or even add a few extra verses of your own.