The students of Kaimei High are going on a class trip, but first, they have to participate in a rope skipping competition to see which class gets the best rooms. Saaya doesn't have an athletic bone in her body, so is worried she's going to doom her class to the worst rooms of all, until the Sket-dan tries teaching her how to skip! Then, the students are on their way, but in the back of one bus, Chuu-sensei is playing mad scientist again, and this time his victims are Bossun, Himeko, and Tsubaki!
And why is there a skull on the lid of 
the case?! Think before you do stuff!
Para colmo puso una calavera en 
la tapa de la caja. ¡Piensa bien!
¡¿Y por qué hay una calavera en la tapa del 
pastillero?! ¡Piensa antes de hacer algo así!
E por que tem uma caveira na tampa 
da caixa?! Pense melhor nessas coisas!