Open Whiteboard for a diagram, worked example or set of notes while an explanation develops. Draw and highlight on the board, add text, and pan or zoom when the idea needs more room.
Undo lets you revise a mark during a discussion. Fullscreen gives the board more space for presenting, and PNG export lets you keep an explanation for another lesson.
The board is temporary and clears when you leave. Export the image before closing the page if you want to retain it.