First, we can say that the selection committee that chose him is highly qualified. We are used to selection panels made up of suitably qualified individuals who are charged with the task of discovering the best person for an important teaching position. In a far higher sense, a selection committee met to discuss who should fill the important role of teaching the disciples of Jesus. Who was on the selection committee? The persons of the Trinity made up the committee, and their unanimous choice was that one of their number should fulfil this role.
Second, we note that he shares the mission of the Father and the Son, which is to bring the blessings of salvation to the world. The Holy Spirit has the same interest in communicating these blessings to sinners everywhere. He is equally passionate in fulfilling the eternal purpose of bringing blessing to sinners.
Third, the Holy Spirit, because he is divine, simultaneously can comfort every believer in Jesus who is in the world. His classroom does not have limitations, either in terms of location or in size of numbers. He is everywhere present and can teach believers in every country at the same time.
Fourth, the Holy Spirit is a superb teacher in that he has no failures in his classroom. True, there are differences in degree in the progress made by disciples, but they all make progress. Nobody in the Spirit’s school will get a failure mark at the end of the school term, which occurs at graduation day when they enter heaven.