The idea of choosing a list of common words as a password is fairly common and can lead to very secure passwords if the selection process is done randomly. The idea entered popular culture with the famous XKCD correct horse battery staple cartoon but is really much older. One of the first systematic ways of choosing the words is Diceware, a method that uses a die and a list of 1776 words. Each word takes 5 rolls of the die (or a single roll of 5 dice) but even a 5 or 6 word password can be chosen reasonably quickly.
I’ve written about Diceware many times in the past and have even provided two computer implementations, one in C and another in Lisp. Both use cryptographically secure random number generation and should be at least as secure as rolling a die.
Over at <Computerphile>, Mike Pound has a video that explains and demonstrates Diceware. He shows how a password is picked and explains why the result is secure. That security remains intact even if an attacker knows you are using a Diceware-like scheme and has a list of the candidate words.
The video is just short of 11 minutes so you’ll probably have to schedule some time or fit it into a coffee break.