May be you were lucky at least for the fact that thre was no female nurses, not always the same in my opinion
The first case related by "ILuvLady docs" seems to me enough credible ; a school physical took place in the nurse'office and the boys were instructed to strip into underwears in their locker rooms by instructions of the male Pe teacher, and then they headed down the corridor being in line and in underwear to the office supervised by him, and they passed by a group of girls who giggled and teased them when they saw them undressed ! why it would not be possible ,? the reverse was certainly not posible but that situation was credible for me
Many guys relates that when a class of boys had their mandatory school physical examinations, they were often instructed to undress in group before at least in underwears, it could be in a locker room, not anlways situated near the office of the nurse, or it could be on benches in the corridor, but in the two cases they could be exposed to the view of teachers of both genders or to a group of girls walking through the corridor where they waited still undressed or crossing their road from the locker room,
many relates that there was not often a mobile partition put at the entrance of the corridor to avoid anybody to come, it was let free for walking while of course such a partition or any mention " forbidden " was put when it was the day of girls physicals .
why that difference ? because the school authorities did not mind a lot about boy's modesty, it was a different way of thinking than today !
as long as the boys were not naked, it was not a big deal if they were seen in just underwears.
There could be also a mess on the schedule of examinations, either in the nurse'office or in a gym which was also frequent in the past when there was a great number of girls and boys to examin, the girls arrived too soon when the exam of boys was not finished and no teacher told them to wait outside so they saw ome boys undressed or the doctor was in a specific hurry that day, it was necessary to win time, the only possibility was to proceed more quickly with the boys whom modesty was not really a concern for adults, so they might undress all together as a group and be examined without partition while the girls were examined later with partitions and they couls see the end of the exam of the boys when they arrived with some boys still undressed..