Note 3 discussed the CAGFD chord shapes. The CAGFD system is a way to find the same chord in different shapes up and down the neck. The concept is illustrated in this diagram from ukulelesafari.com.
The key to the system lies in the order of the letters in CAGFD. The best way to remember it is by observing how similar it is to the word CAGED, which is what the system is called on the guitar. CAGED becomes CAGFD by dropping the bottom horizontal bar from the "E".
THe CAGFD system is based on the observation that when working up the neck,
- the C shape of a chord will be followed by the A shape,
- the A shape of a chord will be followed by the G shape,
- the G shape of a chord will be followed by the F shape,
- the F shape of a chord will be followed by the D shape,
- the D shape of a chord will be followed by the C shape,
- and keeps on going that way until there are no more frets.
If you can follow this next simple piece, all the rest will be mere detail.
Consider the first position C chord, (0003). The next place the C chord appears is as an A shape at (5433). And that's the CAGFD system: C shape followed by A shape followed by G shape followed by F shape followed by D shape. Here it is spelled out for C major.
- The first position C major is (0003).
- The next place the C chord appears up the neck is an A shape at (5433).
- The next place the C chord appears up the neck is a G shape at (5787).
- The next place the C chord appears up the neck is an F shape at (9787).
- The next place the C chord appears up the neck is a D shape at (12,12,12,10).
- The next place the C chord appears up the neck is a C shape at (12,12,12,15), if there are that many frets.
The same exercise for G is GFDCA, which is CAGFD wrapped around to start at G.
- The first position G major is (0232).
- The next is an F shape at (4232).
- The next is an D shape at (7775).
- The next is an C shape at (7,7,7,10).
- The next is an A shape at (12,11,10,10).
- The next is an G shape at (12,14,15,14), if there are that many frets.
All that remains is to explicitly note how the shapes overlap.
- C to A: The bar for the A shape starts at the note on the 1-st string where the C shape ends.
- A to G: The A and G shapes share the note on the 4-th string
- G to F: While very dissimilar fingerings may be used for the two shapes, they share the same notes on strings 1, 2, and 3. They differ only in the note on 4-th string.
- F to D: The only case where there is no overlap. The note on the 1-st string of the D shape lies one fret up the neck than the note on the 4-th string of the F shape.
- D to C: The shapes differ only in the note on the first string. It lies two frets below the bar for the D shape and three frets above the bar for the C shape.
The theory is that memorizing the way in which shapes are related will allow you to know the location of any chord anywhere on the neck. Maybe for some, but it doesn't work for me. If I need a chord up the neck, I don't have time to do the mental calculations before the need passes. Perhaps, its value lies in making it easier to learn where specific chords in specific places, It is interesting to compare the CAGFD system to Calvin Chin's Ukulele Breakthrough (see Note 3). The CAGFD system would have us learn every location of a specific chord, where Chin would have us learn which chord results from moving a specific shape up and down the neck. I find Chin's Breakthrough method works much better for me. However, as they say on the Internet, YMMV.
Because the ukulele has 4 strings compared to the guitar's 6, some have advocated for a more compact system, which is often called GDB. The B shape is the same as the A shape, so GDB is equivalent to GDA. This makes GDB (GDA) a simplified version of CAGFD. That is, GDA is GfDcA, which is cAGfD wrapped around.