Does the sky meet the ground? Or is is an illusion because when we look at
the horizon line, what we really see is the edge of the sphere? It is as
simple as the 'sky meets the ground'? I use that phrase with my students too.
When I do horizon lines, froeground, midground, and background with students
(any age - most recently K-1) I draw 2 quick sketches. The first with one
horizontal line and a house, 2 trees, a fence all on that line. The
second with the smae house, 2 trees and a fence - but I have several horizon
lines, use overlapping, change page position, have a scale change. Then
they talk about both. Then we go from there.