1=C or 1=G means that the song is in a major key, and the solfa 1 corresponds to the note name C or G respectively. This is a manifestation of the solfa method of music's first key.

The "First Tune Solfa" is based on "Moving Do", which means that in the First Tune Solfa, the position and height of Do can move and change, but Each modal tone level has a definite roll call.

For example, no matter in any major key, the first level is sung as Do, the second level is sung as Re, the third level is sung as Mi, and so on. The first-tune solfa method makes the position of each note level relatively fixed in its tonality, thereby forming a typical and stable feeling, allowing people to remember it for a long time, turning it into a perception of music, and promoting the development of musical thinking. form. Its roll call is associated with a certain modal structure, with an obvious sense of modality, and the relative pitch feeling is easy to grasp, making it easy for music learners to accept.

This singing method is based on the mode of singing. It sings the tonic (I-level tone) of the major mode as do, and the others in turn as re, mi, fa, sol, la, and si. It sings the minor tone The main tone of the mode (the first-level tone) is sung as la, and the others are sung as si, do, re, mi, fa, and sol in sequence. In this way, only in C major and A minor, the corresponding relationship between roll calls and note names is the same, but other tones are different. For example, in the key of G major, sing G as do, A as re, B as mi... In G minor, G is sung as la, A is sung as si, and B flat is sung as do... Because of this singing method, the corresponding relationship between the roll call and the note name is not fixed, and the corresponding relationship between the roll call and each note on the piano is also different. Fixed, each note name has different roll names in different keys. When you see a note (such as G) on the score, you must know what key it is. If it is F major, it It has to be sung as re, if it is C minor, it has to be sung as mi... Every time a note is seen, it has to be "converted" to sing its roll call, and then its position on the piano is considered.

Therefore, this singing method is generally not used when learning musical instruments, but it is very convenient for sight-singing ear training and singing some simple songs, because this singing method is very direct for feeling the modal characteristics of the melody of the song.