Did Jiraiya teach Minato the summoning technique? I recently watched the Chuunin exam arc and saw how Jiraiya taught the summoning technique to Naruto.
Jiraiya showed the toad contract scroll to Naruto and wrote his name next to Jiraiya's.

In the flashback that shows how Minato fought with the Kyuubi, Minato entered the scene with Gamabunta, which means that he had signed the contract too.

If the other names written on the scroll include Minato's name, why is his name written first before Jiraiya's?
I've been searching for this, all I could find was:

It's true: "Jiraiya, who took a special interest in Minato and took him on as an apprentice, amongst other things teaching him the Summoning Technique and senjutsu."

As more: "In his youth, Jiraiya taught Minato how to use the Summoning Technique to summon toads. He was able to summon Gamabunta, showing considerably proficiency in this technique as he was one of the few people that Gamabunta would willingly cooperate without hesitation."

We also know that: "Before an animal summoning can be performed, a prospective summoner must first sign a contract with a given species."

Plus: "Not much is known about Minato's relationship with the toads but apparently he was well-respected among them. His only known summons were Gamabunta and Gerotora."

From all of this I can deduce that, or it's something tricky, and since there's no need for a contract (at the willingly cooperate part/well respected thing, or maybe just because Minato was a prodigy), or is a plot-hole, and the animators or Kishi put an accent on Jiraiya and Naruto at the scroll scene and maybe forgetting about Minato.