Teaching some courses in mathematics requires drawing too many shapes or figures (e.g. Geometry, some parts of calculus, etc.) but I am not good at drawing shapes. Of course I can use slides, but I want to use only blackboard.
Question 1: What to do when a math course needs too many shapes/figures and I'm not good at drawing and also I don't want to use slides at all?
Question 2: How to improve my ability in drawing mathematical shapes? Is there any reference?