In the first version of the course, I used the British version of the word "discretisation", that is, with an s.
When I updated the course in 2023, for some reason I decided to change to the American version of the word, that is, with a z.
This is why, in slides and videos, you will see them sometimes with an s and sometimes with a z.
Apologies, pick the one that you like the most ;)
Enjoy the section!