Challenge 2: A Visible Hole Left After Deleting a Face — Solution Walkthrough

The answer:

Per this chapter's own warning box, deleting only the face leaves a
hole edged by the vertices and edges that still technically remain —
those weren't part of what was actually deleted, since only the
selected face itself was removed, not the surrounding geometry
bounding it.

Why the student's expectation didn't match what actually happened:

The student expected the surrounding geometry to close up neatly, but
Blender's own Delete menu treats "delete face" as removing only the
filled surface, leaving its boundary vertices and edges untouched and
now unconnected to any face — exactly the kind of unpredictable
result this chapter's own warning box describes as a common source of
broken geometry.

What the student should check going forward:

Per this chapter's own material, checking the actual result after a
delete — rather than assuming the expected outcome happened — is the
practical habit that catches this kind of mismatch early, before
building further work on top of accidentally broken geometry.

WHY THIS WORKS AS AN ANSWER
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This exercise checks that a leftover hole after deleting a face is
correctly attributed to the vertices/edges surviving that specific
delete option, not a bug or unexpected Blender behavior.