I respectfully disagree. Read what I have written below and cut and paste from an article. It doesn’t coincide with your RE teacher. I have also included a link to the complete article.
I got this from following the link below. I could be reading this wrong, but my understanding is that St. Michael is a Princely Seraphim…a chief Seraphim, so he is in fact the highest ranking Angel right? Again, I could be wrong.
Archangels
Archangels are generally taken to mean “chief or leading angel” ( Jude 9; 1 Thes 4:16), they are the most frequently mentioned throughout the Bible. They may be of this or other hierarchies as St. Michael Archangel,
who is a princely Seraph. The Archangels have a unique role as God’s messenger to the people at critical times in history and salvation (Tb 12:6, 15; Jn 5:4; Rv 12:7-9) as in The Annunciation and Apocalypse. A feast day celebrating the Archangels Michael, Gabriel and Raphael is celebrated throughout the Church Sep 29. A special part of the Byzantine Liturgy invokes the “Cherubic Hymn” which celebrates these archangels and the guardian angels particularly. Of special significance is St. Michael as he has been invoked as patron and protector by the Church from the time of the Apostles. The Eastern Rite and
many others place him over all the angels, as Prince of the Seraphim. He is described as the
“chief of princes” and as the leader of the forces of heaven in their triumph over Satan and his followers. The angel Gabriel first appeared in the Old Testament in the prophesies of Daniel, he announced the prophecy of 70 weeks (Dn 9:21-27). He appeared to Zechariah to announce the birth of St. John the Baptist (Lk 1:11). It was also Gabriel which proclaimed the Annunciation of Mary to be the mother of our Lord and Saviour. (Lk 1:26) The angel Raphael first appeared in the book of Tobit (Tobias)Tb 3:25, 5:5-28, 6-12). He announces “I am the Angel Raphael, one of the seven who stand before the throne of God.” (Tb 12:15)
catholic.org/saints/anglchoi.php