>taught him summoning jutsu
>taught him the rasengan
>taught him the shadow shuriken jutsu. Shown when he hid a second rasenshuriken in the shadow of the first against Tendo Pain.
>taught him the giant rasengan
>improved his battle tactics. Shown when he was able to outwit Kakuzu (a guy survived trying to assassinate Hashirama) twice.
>improved his taijutsu. Shown when he was able to fight the Deva Pain for a bit in base form
>improved his shadow clones creation speed. Shown he made a clone before a bloodlusted Chiyo (who's low kage level btw) could attack Kaskaki
>taught him how to control over Kurama's chakra up to 3-tails
>most important of all he taught Naruto his ideology of peace
Face it. Jiraiya was Naruto's best teacher in the series.