This is an introduction to scales with the Cuatro. There are many kinds of scales relating to all different notes. The importance of the scales is with them you will be able to play different melodies and try to play the basics of any song with them in that particular key.
As you may be able to see in the lesson topics to come, the scales are played using the first three strings on the Cuatro. This is because of the particularities of the B string as it is lower than the F# string before it. At least this tends to simplify things since it is only necessary to worry about 3 strings as opposed to 4.