Answer: That's a topic that may interest others of our readers. I've always liked the moveable Do solfege system as a means of learning to sight-sing; and the hand signs are a useful teaching aid. Moveable Do is the system in which the first note of a major scale is always called Do, regardless of the key.

There's a long history of relating the notes of the scale to the body - going back more than a thousand years to Guido of Arezzo and the "Guidonian hand" image that presented the musical scale on various joints of each finger. The signs you're probably thinking of are those devised by John Curwen in the 18th century, which today are associated with the Kodály method of teaching.

The hand signs cover an octave of a major scale, and each is performed in a different vertical position - the first Do is at waist level, then each of the following signs is higher as the scale rises in pitch, with the last Do coming at eye level.

There's really no way to avoid using a picture for these:

Additional signals have been devised for the altered tones - raised Do, flatted Re, etc., but I'm not sure that hand signs are as useful when they become that complex.

Practica Musica has an exercise in which the student labels notes with the appropriate moveable Do solfege symbol, but the most useful activity for this purpose might be the one called "Display Solfege," in which you can enter the notes of any melody in any key and the program will show you the appropriate solfege syllable for each note. That activity is found under the Scales/Key Signatures topic heading.