I attended non-denominational Christian schools throughout my childhood and adolescence (pre-school, kindergarten, primary grades, elementary grades, junior high school, and senior high school). Because these were not Catholic schools, we didn't have nuns, but the schools were very strict and spanking discipline was commonplace.
From pre-school through highschool graduation, every teacher had a strap and a ruler that were used for spanking the palms of naughty students' hands in front of the class. The straps and rulers were smaller/lighter in the younger grades and bigger/heavier in the older grades. These palm spankings (usually 3-12 swats) were for relatively minor offenses and served as a warning that continued misbehavior would result in bare-bottomed spankings. If a student persisted in his/her misbehavior after a palm spanking, or misbehaved in a more serious way, he/she would have his/her bare bottom tanned in front of his/her classmates.
In pre-school and kindergarten, teachers put boys and girls over their laps and used a hairbrush-sized paddle (like a wooden Fuller hairbrushes, but without bristles) to spank our bare bottoms.
In the primary grades (grades 1-3), the teachers still used "hairbrush paddles" for relatively minor misbehaviors. But they also used a larger "primary paddle" for disciplining more serious misbehaviors. The primary paddle was still small enough to be administered with a naughty boy or girl laying across the teacher's lap.
In the elementary grades (grades 4-6), the teachers still used the "primary paddle" (over-the-lap) for relatively minor offenses. But, a larger "elementary paddle" was used for most misbehaviors. The elementary paddle was too big to use effectively with a boy or girl over the teacher's lap, so the student would be required to bend over the "punishment desk", with his/her bare bottom facing the class. The punishment desk was just a traditional student school desk, with a hinged lifting desktop (with a storage area beneath the desktop -- straps and paddles were usually stored inside), that was at the front of the classroom, next to the teacher's desk.
In junior high school (grades 7-8 ) and senior high school (grades 9-12), bare-bottomed punishments were administered only by the P.E. coaches, inside the boys' and girls' locker rooms. For example, if a student misbehaved during mathematics class, the math teacher would give him/her a "pink slip" to take to after-school detention period in the gymnasium. The naughty boys and girls would have to change into their P.E. uniforms and do military-style physical training (push-ups, sit-ups, pull-ups, and running laps) with the coaches acting like drill instructors. For some of the naughty students, the P.T. was the extent of their discipline. But, when spanking was also required, for more serious punishment, it was administered after the P.T., when the boys and girls returned to their locker rooms to shower and change back into their regular school uniforms. After showering, before even being given a towel to dry off, a student who deserved bare-bottomed corporal punishment would be required to fetch either a strap or a paddle (they were hanging on the wall in the showering dry-off area). Each locker room had an old decommissioned gymnastics vaulting horse in the showering dry-off area. Naughty students would be required to give the strap or the paddle to the coach and then straddle/bend his/her still-wet naked body over the horse. The naughty students in the locker room would witness each others' bare bottoms being tanned (usually 5-12 swats). In the boys' locker room, it was not unusual for a boy to get hard before, during, and/or after receiving a tanning. My high school girlfriend confided in me that, while less obvious, she and some of the other girls sometimes also experienced some sexual arousal when receiving locker room punishment. After a student had received his/her punishment, the coach would sign his/her pink slip. The student would then be required to take the pink slip home and obtain a parent's signature. For me and my sisters, bringing home a pink slip meant that our already-sore asses would have after-dinner appointments with Dad's razor strop in his workshop.