Though from an entirely different era than the songs covered in the article, I feel I must share some of my favorites here:

* I'm Gonna be an Engineer - Pete Seeger

  https://youtu.be/cgzl1Sai4Y0?t=25

* What did you learn in school today? - Pete Seeger

  https://www.youtube.com/watch?v=VucczIg98Gw

* Buy a Gun for Your Son - Tom Paxton

  https://youtu.be/WphNO24h9nA?t=51