Math teachers always have to draw shapes. We're always graphing lines or parabolas or circles or ellipses, or perhaps drawing solids like spheres or cones or cylinders or prisms.
The Holy Grail for math teachers is to draw the perfect circle. On an overhead projector it's nigh impossible; it's not quite as impossible on a chalk/whiteboard, where you can pivot your arm around the shoulder socket and make a good, large circle, but perfection is difficult. Some teachers can go an entire career without ever achieving this pinnacle of performance.
I have achieved--and on an overhead, too:
Totally freehand. While I was talking. Students tell me I was looking at them, not even looking at the overhead. Totally in the moment.
Bow, my minions!