class students bow to their teacher, or sensei, and to a photo of judo's japanese founder, gigoro kanokano struggled with martial arts because he was very small. >> so he wanted to prove that he could beat the larger competitors. he developed judo so he was able to do that. >> reporter: taraje williams-murray also knows how to win. he's a national champion and competed in the 2004 and 2008 olympic games. >> in competition you can either throw the person onttheir back. if they hit flat, both shoulders hit the mat, it is a full point and the match is over. you can also pin the person for 25 seconds. you can choke them until they tap. >> reporter: you heard him correctly. judokas, people who practice judo, can choke their opponents. >> you can use the gi to wrap around their neck or you can wrap your arm around their neck too. just no hands. you can't choke with your hands. when you start to feel as though you may pass out, you tap and the other person releases. >> reporter: the gi, or uniform, is a key part of every match. judokas grab their opponent's sleeve, lapel or pants to gain cont