Phrasing, the art of hearing it. Haydn, Sonata Eb I – hob. XVI:49.
So not forcing the student to play what’s written “because that’s what one should do”, but tempt and challenge: just try it, try it seriously, with attention. With an open mind and ears.
To train the skill of listening, focused listening, detailed listening. While you play. Which is not that easy at all.