Pencil Shell

Pencil Shell aka A Pencil Cannonball aka Pencil Rocket (Korean: 연필포탄, lit. Pencil Shell) is a North Korean animated work encouraging children to study geometry by giving them examples of its usefulness in times of war.

Plot
The short begins with a young boy chasing a rabbit with a stick, before his older brother tells him to do his homework. He is displeased by having to do so, and instead doodles a US Army helmet, which he pretends to shoot at with his compass. He eventually falls asleep to experience a nightmarish invasion of his homeland by anthropomorphic American naval vessels. he mans some artillery, where geometry becomes important as it is used to calibrate the shots. At first defense of the homeland is going well until a miss calculation causes the boy to miss an incoming projectile, which allows the American vessels to break though. The kid's friends come to his aid, but it seems they are too late. The boy awakes from his dream, with a new found drive to do his homework. The film ends by explaining the boys major mistake (he had one of his tools in the wrong position, thus he was unable to accurately read the angle of his artillery piece).