Janken (じゃん拳,janken?) is the Japanese equivalent of Rock Paper Scissors, but taken to a whole new level in terms of usage and importance in daily life. If there is ever a clash of opinions between two people in Japan, more often than not this potentially embarassing situation will be decided with janken. Who gets to eat the last Rolo, you or me? What DVD should we rent, Terminator 2 or She's All That? Who should take the rap for our company's bankruptcy? etc. Japanese children will play janken tens if not hundreds of times a day, so it's important to know about janken if you're going to be teaching in schools.
Various forms of janken exist all over Japan. The phrases and sometimes the hand gestures can vary from region to region. Ask a child to teach you their version. The version described below is the most common.
The good news is that the rules and gestures are the same as in English. Rock beats scissors, scissors beats paper, paper beats rock. Rock is called "Guu" (ぐう,"Guu"?). Scissors is called "Choki" (ちょき,"Choki"?). Paper is called "Paa" (ぱあ,"Paa"?).
There are many different ways to play Rock Paper Scissors using English and different teachers will use different versions. The key thing is to pick which version you're going to use and then stick with it in all your classes.