Modulation through unprepared cadence 4/6 chord of any new tonality

The simplest modulation: just take the tonic (cadence) 4/6 chord of any new tonality, and reinforce it by adding dominant 7 and the tonic chord. From whatever tonality to whatever tonality you modulate in that way, it will all sound well.

This should be taught as the foundation for modulation. This exercise expands the sense of tonality, and destroys whatever mental auditory limitations the student of harmony may have before the beginning of learning.