At Deering's web site, they have a blog entry Learning Banjo by Ear for Beginners. The third step says, "Sing that melody aloud in the key of G. (keep strumming that chord if you need a reference point)."
So, there are beginners, and those of us who are REALLY beginners. :)
If I'm singing a song and strumming a G chord, how will I know I'm singing in the key of G, versus another key, or none at all? Is it possible to be in a wrong key where it still sounds okay, or will there necessarily be disharmony?