Hi Seamus, if I can answer for slim.....play a three string Dm.

If I can go back to my first post for a moment:

As I said there are many OTHER ways of determining the proper key. The way I described gets a novice into understanding that "intervals" and "triads" (major and minor" need not be theoretical mysteries. A little memorization can be a huge help, and it gets you into theory pretty painlessly and with some immediate practical results.

My problem with learning to read music as a kid (I resisted and DIDN'T) was that I couldn't see WHY it would make a difference. If learning a little theory (and the names of the notes on your first string) can enable you to identify recorded keys within a couple of days of practice, then it provides almost immediate results....and that has to be an enticement.

Rick