Formal outlines may well be the least useful kind of outline,
but anyone teaching writing should know their essential elements.
You won't need to teach formal outlining until after
students are competent writers: informal outlines are just
as useful for planning purposes as formal ones.
Students who are not college-bound don't ever need to write an
outline using fancy outlining symbols. Even those headed for college
will rarely be required to use formal outline format.
Formal outline format
All outlines (formal or informal) are built on a grid. The diagram
at the right shows a formal
outline superimposed on an informal outline grid colored to
emphasize the relative sizes of ideas.
Any two rows that line up at the left margin are equal-sized
ideas. A row that is beneath and to the right of another row is
a subdivision of the upper row idea.
The main points of the outline are written starting at the left
hand margin and numbered with Roman numerals, I, II, III
.
(Maybe some of your students, like mine, call them "Roman numberals.")
The next lower-level points, one column to the right of the
main points, are labeled with normal English capital letters,
A, B, C
. Two columns to the right of the main point, the third
level is labeled with Arabic numerals, 1, 2, 3
.
Each label is followed by a period. Items are arranged
so that all the periods after the Roman numerals line
up, all the periods after the capital letters line up, and
all the periods after the Arabic numerals line up.
Students should rarely need more than three levels of detail,
but if they do, the outline numbering scheme of formal outline
format alternates numbers and letters from left to right across
the grid:

The subdivision rule: no A without B
When you divide anything you get at least two pieces. Therefore,
formal outlines, which show the divisions of
topics, can't have just a single subpoint. In
other words, there can be no point A unless there is a point B,
no 1 without a 2.
The subdivision rule suggests one big reason
a formal outline is a poor planning tool for writers: often the
best way of developing a thesis for a particular audience means
using a single anecdote or illustration for a point. If the prohibition
on single subpoints means Joshua cannot make himself a note
about what evidence he intends to offer, he may lose that idea
before he gets ready to write.
A planning device like the outline
template lets Joshua record in one place everything he needs
to prepare to compose without worrying about the technical points
of formal outline creation.