Assembly: really gets you to understand that you are contending with a computer chip, and that anything interesting that you want to do requires abstraction.
This is only tangential to your point, but I did remember (now-defunct) game studio Zachtronics put out a few games heavily featuring assembly: TIS-100, which directly revolves around programming the titular computer in its own version of assembly, and SHENZHEN I/O, which centers around building embedded systems and programming the microcontrollers contained within.
The company's catalogue is completely free for schools under the Zachademics program, so you could use them to show how assembly programming's like if you were running a school.