Use course tools>>Virtual Classroom>>Use whiteboard tools
With the line tool, you can draw a straight line as well as a line with several segments, as shown here:
(Optional) Select Line Width from the Whiteboard menu to select a line width for the line.
(Optional) Select a color for your line.
Click the slanted line tool on the whiteboard toolbar.
Click at the point on the whiteboard at which you want to start the line.
(Optional) Click once to change directions.
Double-click to end the line.