I'd try to get him on a balanced diet of formal verse and contemporary free verse to understand and appreciate that free verse follows a form, usually one the poet has created - and it shouldn't be confused with lineated prose.

Contemporary poets: Mark Strand, Louise Gluck, Rosanna Warren, Frank Bidart, Robert Pinsky, John Ashbery, Adam Zagajewski

Others of interest: Keats, Hart Crane, Auden, Frost, Elizabeth Bishop, AE Housman, Edward Thomas.