I am not sure why they don’t. A resource I stumbled across that has worked really well for us is called Teaching American History with Favorite Folk Songs by Scholastic. It includes a CD of the 12 songs that are introduced. It is fun to see how excited the kids get when they read about a song in their history studies that they have learned in our folk song time. For example, “Revolutionary Tea,” which happens to be our favorite song in the book, was mentioned in Toliver’s Secret. My husband thinks the version of that song on this CD is great, (and he is pretty picky!) We take the CD on road trips and just sing our little hearts out! The songs have become quite meaningful to us. I think this is because we have developed such relationships with the particular events/time periods. And this is largely due to the wonderful living books we have read.