Video call and share writing This summer, I will be having meetings with my Ph.D. advisor, and since he's traveling, we'll be meeting via Skype or FaceTime. Since we are working on mathematics, we need a way to see each other's writing, so we can quickly suggest ideas to each other and talk about them.

He will be using a MacBook Pro 2017 and I'll be using my iMac 2018 or MacBook Pro 2017.
I have an iPad pro with Apple Pencil; I'm not sure if he does. I mention this because it may be a solution that we have separate writing apps open on our iPads even as we FaceTime. In case he doesn't have an iPad already, he will of course need to get some device that has the ability to receive handwriting.

What is the best solution? Including what gear he'd need to have.

This would also be a great question for online tutoring.
AWW App

From a simple Google Search (and some testing) I have found a WebApp that allows real time collaboration on a whiteboard. From my tests the board is updated once the mouse is released. 

It works in realtime on Mac's and iOS devices meaning you and your Ph.D. advisor could use it at the same time no matter what device you guys are on.

You can...


Draw with different colors
Type text
Add Shapes
Create Post-it notes
Add Pages
Export your board as a PDF or Image
Save your board for future use
Add collaborators


Extra premium features are available.

Note: I am in no way affiliated with this company or product and will not be impacted by the purchasing (or not) of this product