Genk yshi may be used with a pen, a pencil, or an ink brush, and is used especially by primary and secondary students.
Genko yoshi may be used with any type of writing instrument (pencil, pen or ink brush), and with or without a shitajiki (protective "under-sheet"). Primary and secondary students in particular are required to hand in assignments written on genko yoshi, and essays for school entrance examinations are also written on the paper, making knowledge of the correct way to use genko yoshi essential. 
