Off Hand Drawing
The challenge is simple enough: draw something, anything, but using your off hand. If you’re a lefty, use the right hand; righties, use the left. If you’re one of the lucky few who are ambidextrous… I dunno, use your foot or your mouth to draw.
I like this challenge because it shows, in a way, that drawing is a mental process more than a hand one, and while your off hand is not as practiced as your usual one, your technique should be the the same.
As a hint of help, try making mirror gestures of what your usual hand would do. Years ago my father damaged his drawing hand for months and had to work with his left hand to design his house plans, and he discovered that he was able to sign his name in a mirror motion to what his right hand would normally do. Once he figured that out, he would start his drawings from the opposite side of the page, drawing the lines going in the opposite direction to what he usually did, and it made his drawings a lot more recognizable by his crew of technicians.