Challenge 1: Suggesting Mode vs. Editing Mode, Side by Side — Solution Walkthrough

Steps:
  1. Switch to Suggesting mode (top-right mode switcher).
  2. Select an existing sentence and rewrite it.
  3. Have a second viewer watch the same document live while you type.

What the second viewer sees while you type in Suggesting mode:

The original sentence stays fully visible, shown with strikethrough
formatting in a distinct colour, while your new replacement text
appears alongside it, underlined, in that same colour — both the old
and new text visible at once, clearly marked as a proposed edit, not
yet an actual change to the document. A small icon or marker typically
appears in the margin indicating an active suggestion at that
location.

How this differs from the same edit done in Editing mode:

In Editing mode, the second viewer would instead see the original
sentence disappear and the new sentence appear directly in its place,
live, exactly as Chapter 2 described — with no strikethrough, no
underline, and no indication that this was ever a "proposal" rather
than a finished, permanent change. There would be nothing to accept
or reject afterward, because nothing was ever held apart from the
actual document text in the first place.

WHY THIS WORKS AS AN ANSWER
------------------------------
This is the direct, hands-on confirmation of this chapter's own core
distinction: Suggesting mode preserves BOTH the original and proposed
text, visibly, for anyone currently viewing — Editing mode simply
replaces the text outright, with nothing preserved to review or
reject later.