Whiteboard with coordinate plane overlay?

Hi all, I use zoom to tutor students in math. Often I need a grid or coordinate plane as an overlay to the whiteboard. But, I don't know either how to drop an overlay - maybe a grid I make in excel - onto the whiteboard, where I'm still able to mark the grid with numbers, lines, dots, arrows, etc. 

Or, is there already a pre-made coordinate plane through zoom? 

Thank you for your help.

deb