Intel 8080 processor from 1974 only had 4,500 transistors.
It can certainly be an educational project (and with current technology it is affordable) to tell students to try to recreate it without examining the original.
They’ll learn some humility at least.
The Intel 8086, the foundation of the IBM PC, whose instruction set is still contained in all Intel x64 processors, had 29,000 transistors.
The current generation Intel 12900K has about 3,000,000,000 transistors.
I gave high school students lessons on digital logic gates. Eventually they were exposed to the necessary logic to implement an AVR ATMEGA328 uP instruction set. A few of them were thrilled and went on to study CS or digital electronics in college. The majority just didn’t care.