A view from the other side, not as a teacher but a parent. I spanked my daughter when my wife and I considered it necessary, not a frequent occurence, it happened no more than five times in total. The routine was always the same; she pulled her own
knickers down, then over my knee for enough slaps to make her cry (three was usually enough).
The last time was when she was fifteen. I decided she was too old to go over my knee and I wanted to avoid hand-to-bottom contact so she was required to bend over. There was an argument about whether she had bent over far enough but I then pulled her frock up and her
panties down, another argument but I insisted they stayed down.
I then smacked her hard with the back of a long handled clothes brush. The first stroke brought a loud "Ow" from her; with the second she shot upright, clutching her rear and bawling. To my shame I then spoke the cliche "Bend over, we've barely started". She bent over again and I delivered the third stroke. This almost reduced her to hysterics but she remained in position waiting for the fourth.
But I suddenly realised that I was enjoying it. The fourth stroke never came, I told her to stand up and pull her pants up. And I never ever spanked her again.
From eight to twelve, "pants down" was to make sure that the spanking hurt. At thirteen and fifteen I thought I was using it to add humiliation to the punishment to persuade her that it wasn't worth risking a spanking in future. But now I'm not sure.
Fortunately for me my daughter, now middle-aged, has never held it against me and we are very close. She did tell me that the waiting for me to come up to the bedroom was the worst part.