Annotation & Whiteboard
Hmm.... didn't think about just how many options there are! I will probably have to redesign this page, or split up my choice board, above.
Here is a more comprehensive list of Annotation Tools:
Google Slides (sheet in background)
Flipgrid now has a whiteboard feature built in to Shorts. Richard Byrne has made a helpful video showing how it works. It lets you draw with different colours, while you record. Then switch back to the camera mode. Great for students to demonstrate thinking, e.g. math problem solving.