The Linear Line Assignment from illustrationclass.com:
Your assignment is to draw a continuous line drawing of each of the five listed items below. The key to this style is that it be one single continuous line that makes up the entire illustration. It can overlap but visually it has to be one line without any breaks. Sounds simple but it can be tricky.5 Drawing Topics- Light Bulb- Lizard- Fish- Car- Face/Head
Here's a little line inspiration from Laura Ljungkvist, Mo Willems, and Alexander Calder. And I'm adding cartoons by UPA/Bob Cannon and Bob Cannon/Dr. Seuss. (So what if the lines aren't continuous.)
(Thanks to Von R. Glitschka)