Doodle

A doodle is a type of sketch, an unfocused drawing made while a person's attention is otherwise occupied. Doodles are simple drawings that can have concrete representational meaning or may just be abstract shapes. 
Stereotypical examples of doodling are found in school notebooks, often in the margins, drawn by students daydreaming or losing interest during class. Other common examples of doodling are produced during long telephone conversations if a pen and paper are available. 
Popular kinds of doodles include cartoon versions of teachers or companions in a school, famous TV or comic characters, invented fictional beings, landscapes, geometric shapes and patterns, textures, banners with legends, and animations made by drawing a scene sequence in various pages of a book or notebook.