I like the idea to teach the LOS rules also with a profile view of a landscape. Here you find some more examples for the plateau effect and the blind spot.

(Examples in profile view and in map view are not linked to each other)

Concerning the black soldier and the spotted green/red soldiers: Think about LOS always works in both directions!

Remember: The obstacle covered by a blind spot by another obstacle can be seen by the spotter, but the unit on the ground between the trees or buildings can't be seen in such a case.

Note: In the previous version of my post there was an error in the examples: I treated slopes like obstacles. As clarified in the latest rule version (PoH): "A clear hill hex does not create a blind spot for units firing from higher up along the same hill slope." So only if another hill is not at the same hill slope it must treated as an obstacle.