Imagine you want to teach kids how computers work. You can tell them about input and output devices, RAM, ROM and storage. But if you want to tell them about the CPU, it is like a black box, where you don't know what is happening (other than "It's calculating").
At this point I suggest to tech 6502 assembler. The 6502 syntax is easy to learn, there are plenty of books about it and if you want to demonstrate it you could use Hans Ottens KIM-1 simulator. You have a steep learning curve and every tool for this is free.
Additionally the kids need to learn about the binary system, the hexadecimal system and boolean operators.

How are programs stored, how are they executed, how does the computer boot up to a point where it understands your input. And so on. Everything is hidden in the KIM-1, this 6502 "demo" device, which was build in 1976 to show people the possibilities of the newly developed CPU. Take a look at this sheet:

exactly in this document you can see how computers work. that every command equals a number. What is it? Simply a handwritten program from 1976. Every command is rtanslated by hand into it's corresponding hexcode. You had to look it up in a table: STA, the command for storing a value direct in the Accumulator is "A9" so, storing the value $30 is "A9 30" simple, heh? Everything is about manipulating the memory in some way. Together with counting, looping, comparing you get a complete set of commands.

Sidenote: my son had to learn 6502 assembler in his computer science studies. (something I could help him with :D )

I may sound like a white old mn (which I am) but this is something kids should learn before graduating. I am everyday impressed what this little CPU engineered in 1975 is capable of.