Tipical example of how to use what could seem a classical to develop muscles and positions for a jazz voice. And also classical example of how to develop a voice without collapsing and remaining restraint in the repertoire/style performance sound. Meaning by that that we can (as I always do, and perhaps we should) think separately the training of the voice and the singing so to have the freedom to use exercises and vocalisations to obtain the voice we can use without straining and yet prepared for then practice the style and the repertoire and performances. It can seem the same thing, no there is a useful great tool in this way of proceeding. The huge difference with classical purposes is where to put the stretch horizontal of the same position and where to make the turn or the kind of copertura if you prefer getting downward (and not upward in positions as I do with her) in the tessitura.
*One notation for professionals and teachers: why do I have her sitting? Of course it is on purpose and precisely thought. 1) as you can hear she is not accostumed to the kind of precision in position I am asking her 2) we worked on gaining enough elasticity in breath (intending breath as in Italian Belcanto as the force of the front (not the low abdominals we use to support) and not from the back) 3) for the two previous points I can avoid excess of intensity in her vocal folds and not specific work of the breath with the sitting position and the feet and legs just to have a continuity in elasticity but not as producer of strength. Once integrated breath/positions she will be allowed of using legs, feet and hips but not in these kind of vocalisation (if used we will develop a classical sound or a too pushed one for the jazz singer she is).