They don’t use those terms anymore as I discovered when talking to a great friend who is very decorated by the establishment for being a “Head Teacher”.
Master of Ceremony, Master Switch, Gramdmaster
Master Boot Record
Master of Social Science ... ohhhh
Dammit I got called to the head default room again...
None of which have any association with master/slave, unlike git where the convention of calling the default branch "master" comes from BitKeeper, with its master/slave repositories.
Grandmaster Flash is ok i guess :p
I honestly can see middle schoolers snickering at the fact that their school's authority figure is seriously and officially referred to as "head" teacher.