About seven years back I got this document from Casey Jones, then Associate Head Coach (Defense) for Ohio State University. It went through in some detail how OSU played defense and how the coaches went about teaching the system to the players. This document goes through some of the steps on how to teach the OSU defensive zone system to your team. The handwriting in the document is a little hard to read so I am also including a link to a version I created in DrillDraw that is easier to read but contains the same information. I hope you find this document helpful in teaching defense to your team.
Both documents are in PDF format and pretty large so be patient while they download.