The evolution of CPUs was born with the process of nano technology advances and mass production. You could start with the current price/perfomance chart AMD vs Intel then go back in time to 386's. Touch on the bases that technology has double in short times like the memory going from 32/64/128/256/512/1024.
For extra credit you may want to talk about quad cores and dual cores and how they have driven the price of single/dual cpus down the price ladder.
Im not a prof but if i had to write the essay then thats how i would go about with it.