Why a Tetrachord?
A tetrachord is four consecutive notes of a scale. In C Major that is C to F, D to G, E to A, and so on. Coincidentally, your hand has, excluding the thumb, four fingers. So, play an ascending tetrachord with fingers 2, 3, 4 and 5. Play a descending tetrachord with fingers 5, 4, 3 and 2.
Goal for the Exercise
With the notes so close together, you will quickly discover that flexibility of the hand is the key to this exercise. This practice is critical for the chromatic button accordion (CBA) because compared to the linear layout of the piano accordion the CBA requires the fingers to stumble over each other when playing tetrachords.
Play C Major Scale Tetrachords on Outside Three Rows
Play the first tetrachord, C to F, up and down using the fingers in order, 2 to 5 going up and 5 to 2 going down. Then go up a scale step and play the tetrachord D to G in the same manner. Continue on the next scale step, E to A.
Repeat the sequence going up the scale steps until you have done eight sequences and reached the octave. Then play eight more sequences descending step-wise from the octave until you are back at the starting point.
Extend the exercise by playing it in various keys and also the range of the exercise into upper and lower octaves.
Repeat Exercise Across the Outside Four Rows
Eventually, revise the exercise for four rows. This will change the fingering patterns.
Repeat Exercise Across the Outside Five Rows
Finally, revise the exercise for five rows. Again, this will change the fingering patterns.
