A method of teaching is likely to be rejected as unpatentable under §101 (commonly used to reject software and business methods, but it seems like teaching would be treated similarly). @EricShain is likely correct: copyright will probably be more useful to you.
"Section 101" is part of US patent law, officially numbered 35 U.S.C. §101. It says:
There are certainly many patents that cover educational systems. A few that came up in a quick search:
Online educational system with multiple navigational modes
Vertically integrated mobile educational system US9324240B2
Real time learning and self improvement educational system and method
On-line educational system having an ...