Explain Everything is a great application that lets you use your iPad to draw, diagram and annotate over just about any file. This, along with a self-contained recorder for both audio and video, makes this a perfect addition as a tool for instruction.
Explain Everything comes in two flavors: Basics and the Collaborative version. We recommend to start with the Basics version, then, if needed, you can upgrade to the more collaborative version.
UML IT can supply a license for this software as needed, by request.
Go here for some tutorials: https://explaineverything.com/step-by-step-guides/