Another way to reduce anxiety about shifting is to introduce the higher positions using natural harmonics. Harmonics are produced by lightly touching the string at certain nodes throughout. The easiest harmonic to produce is halfway between the bridge and the nut. Touching this harmonic will produce a pitch one octave higher than the open string - I will refer to this as the first harmonic.
Moving the hand towards the nut will produce three more solid harmonics - The second harmonic is a perfect 5th higher than the first harmonic, the 3rd harmonic is a perfect 4th higher than the second harmonic, and the fourth harmonic is a Major 3rd higher than the third harmonic. On the G string, it will produce the ascending pattern - G-D-G-B. This same pattern can be played starting at the first harmonic and moving toward the bridge - G-D-G-B. Additional harmonics can be played moving toward the bridge. These harmonics will be used extensively in advanced solo playing (especially on the double bass). The movie demonstrates the following harmonics moving from the first harmonic towards the bridge - G-D-G-B-D-F-G-A-B. These harmonics can be found on all the strings, but are easiest to produce a long thin string.
Try these exercises with your students:
1) Play the pattern (G-D-G) with one finger moving towards the nut, and then toward the bridge. Repeat on different strings. Try adding additional harmonics as students get comfortable with this exercise.
2) Shift between octaves using harmonics (e.g., first harmonic D on D string to 2nd harmonic D on G string). Use different finger combinations (e.g., 3-1, 1-3, 3-3, etc). See movie for example.
3) Shift from a harmonic to a stopped pitch (e.g., first harmonic D on the D string to D on the G string - pitches should match. Use different finger combinations. See movie for example.