In Naruto, the relationship between the students and the teachers are very important. One can't be a ninja by simply graduating from the academy...they have to work hard to be keep their title as a genin (appretence ninja) by working under the supervision of a jounin (elite ninja). Great teachers make great students...and this is how the tree revolves around Kakashi.

	First Generation 1st and 2nd Hokage >> 3rd Hokage The 3rd Hokage was a genin under the supervision of the 1st and 2nd Hokage. With training with one of the best ninjas in the Hidden Leaf village, it's no wonder how the 3rd Hokage got so great.
	Second Generation 3rd Hokage >> Orochimaru, Jiraiya, and Tsunade The three genins that trained under the 3rd Hokage were Orochimaru, Jiraiya, and Tsunade. These three students eventually became the three legendary ninjas of the Hidden Leaf village.
	Third Generation Orochimaru >> Anko Although this branch has nothing to do with Kakashi, it is pretty important to point out that Anko was Orochimaru's ONLY student...which is odd because normally genins are split up into groups of three. Although Anko is Kakashi's Jounin level, she's no where near Orochimaru's.
	Third Generation Jiraiya >> 4th Hokage As weird as Jiraiya might seem, it was actually him that was the jounin who trained the 4th Hokage (whose real name is still not revealed in the manga). The 4th also had two fellow genin team mates that worked under Jiraiya.
	Fourth Generation 4th Hokage >> ??, Obito?, and Kakashi Here we go! It is revealed in the manga that Kakashi's teacher was actually the 4th Hokage himself! Although the names of his teammates are still unknown (although it's hinted that the other boy in the team may be Kakashi's dead best friend Obito)
	Fifth Generation Kakashi >> Sasuke, Sakura, and Naruto Which brings us to the present storyline in Naruto, Kakashi is currently training Naruto, Sasuke, and Sakura (who are the only students he EVER accepted from the academy).