Jon,
as you might remember I am a professional software programmer.
I think the above example should need no comments.
I myself use comments mainly to write at a function declaration what the function is supposed to do and what the parameters mean, what is returned and what happens if errors occur.
Elsewhere in the code I only write comments if I do something in an unusual way (because it might be more efficient...)
But in a teaching environment, I also insist on more comments than really necessary. I offen recommend to write the algorithm first as comments only like in

//for each of the five employees
//    ask for hours worked
//    check if more than 20 hours
//       yes: multiply by 4
//       no: multiply by 3.75
//    output calculated pay

and then (after once again thinking about it) replace each line of comment by the actual code (or write the actual code before the comment).

MudGuard (still remembering Great Orme!)