According to USBE Rule 277-522-3, mentors need continued professional development. Lead mentors can provide ongoing training for mentors in their schools.
Here are some ideas that can be used:
Judy Jackman's Strategy Page
Christenson, Matt. How to Develop Rigor in the Classroom. The Art of Education. Retrieved from: https://www.theartofed.com/2017/09/07/develop-rigor-classroom/
The Teaching Channel
Aguilar, Elaine. How to Structure a Coaching Conversation. Education Week Teacher. Retrieved from: http://blogs.edweek.org/teachers/coaching_teachers/2018/01/how_to_structure_a_coaching_co.html