Lesson 22 - Cell Coordinate to World Coordinate Math Explanation

[ghost]

Issue description:
The math used for the conversion from cell coordinate to global coordinate is not explained. A suggestion I have is to add a simple explanation why the cell coordinate is multiplied by its size then added to half its size. Other than that, lesson 22 is very informative.

[JAlbair]

Up until Lesson 22, things have been going great! Hitting #22, I felt quite lost and I think it's because the math is not explained.

Even here:

I actually can understand the math (I understand the values that are output), but I don't understand WHY we are doing this. It seems too abstract maybe?
The practice in 22, even after looking at the solution, is not helpful to me, for this reason.