Am I wrong in thinking that we're getting a bit "swamped" (am I allowed to use that phrase, now?) with all this discussion about modes and scales, and ascending and descending melodic/harmonic minors, etc.? If this thread is for the assistance of jeepman, it seems to have taken on a life of its own! Folk Music, it seems to me, whatever the technicalities of the more pedantic definitions, is about the learning of songs and music by ear ( an Aural tradition ). Therefore an understanding of musical theory is totally unnecessary for the enjoyment of and performance of, Folk Music. That is not to say that the theory of harmony isn't interesting, or that understanding it may not improve one's ability to shall we say, arrange songs or tunes. To get to the heart of the matter shall we say that most tunes with which we are familiar are sung(played) on a series of notes which are called a scale, and probably the commonest one is a major scale which most people will be familiar with as doh ray me etc.. Whichever note this particular tune takes as its "tonic" is said to be "the key" it's in; its tonic note being the starting note for the series of notes for this scale. The 3 chord trick refers to the fact that this run of notes can be harmonised (Accompanied by) three chords based in turn on the note doh, the note fa, and the note soh, of the scale we were first thinking about! For convenience(and to help us do facile things such as playing in tune together!), each note is given a name and this name refers to a specific pitch determined by the frequency of vibration necessary to produce that note, eg "A" is 444 Hz (cycles per second) I don't suppose this garbled nonsense makes much sense, but here's a tip. If you're playing along with someone in say the key of C, and you're playing C, and the chord changes,(not the key) change to G, while keeping strict time. If this is the wrong chord, keep playing IN TIME for a regular number of beats, and change to F. This often works and makes it sound as if you are putting in a passing chord, and that you have a superior knowledge of Harmony to the main player! If it doesn't work, Shut Up!