What are the best methods for conducting usability testing with people who are neither experts nor end-users?

My team and I have developed a prototype of an augmented reality mobile application for teaching primary school students human anatomy.

We are going to do a usability testing and evaluation with the primary school students using FUN toolkit, and we are also going to conduct an expert review using heuristic evaluation and cognitive walkthrough.

Furthermore, we also want the teachers to test the app, and to evaluate the usability in the context of their students' usage. However, the teachers are neither usability experts nor end-users so what is the most appropriate method for them regarding usability testing, survey design etc?