I did have a teacher change my diaper before in Kindergarten.
I had wet my pants and so the nurse put me in a diaper and then my teacher was given a few Pampers diapers in case I needed a change.
So my teacher laid me out on the floor one day in the back of the room and changed my wet diaper in front of the class.
I had a few kids laugh at me but the teacher said if they kept laughing they would be getting a diaper put on as well.
And since my pants were wet because my diaper leaked I was sent back to my desk wearing just the Pampers plastic backed diaper, shirt and my socks and shoes.
I was embarrassed but also was enjoying being dressed like that at the same time.