Cross-Species Switches

Cross-Species Switches are a type of transfiguration that is caused when Transforming Spells are modified in certain ways. They are presumably a type of Switching Spell that changes certain aspects of different species and may therefore be Trans-Species Transformation.

The fourth year transfiguration students at Hogwarts School of Witchcraft and Wizardry were given homework on Cross-Species Switches, as listed below:
 * 1) Describe, with examples, the ways in which Transforming Spells must be adapted when performing Cross-Species Switches.
 * 2) If bodyweight is A, viciousness is V, intended transformation is T, wand power is W and concentration is C, and assuming T=(WxC)/(VxA)xZ then what does Z equal?

Appearances

 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Goblet of Fire