I teach in this area, and have vocational certification at secondary and
post-secondary levels.

This is my rule:  TWO SPACES BETWEEN SENTENCES.

You do not change your standard.

In fact, my extended rule is that IF the punctuation has a period at the
bottom:  :, !, ?, or . --then it is two spaces afterwards (unless it is
followed by an end quote or it is at the end of the paragraph.)

If it has a comma at the bottom (, or ;) then it is one space afterwards.

MY BACKGROUND:
I used to do professional, computerized phototypesetting for things such
as the Minnesota Supreme Court Journal, and other publications.

HERE IS SOME OF MY JUSTIFICATION:
1.  If you have good software, then the software can decide when to use a
thick- or thin-space when doubling spaces between sentences.  Professional
software which can do this includes the kind of technology where the
operator can make end-of-line decisions for greater aesthetics and
precision.
2.  As I said above, you "keep the standard."
3.  In some circumstances, when you don't have professional software--for
aesthetic purposes, you may want to keep certain text together on a line,
and with normal software (such as Microsoft Word, etc., where you cannot
adjust the spacing BETWEEN LETTERS IN A WORD), then to keep text together,
on a case-by-case basis, that is when I will violate my own rule.  BUT
NEVER TEACH YOUR STUDENTS to consistently break the rule to save space in
a text (i.e. for the school's yearbook or newspaper).
4.  The double space between sentences helps your reader.  Whatever helps
your reader is a plus.  The period is a very small "speck" on a page.  It
is an excellent indicator of an auto-glottal stop.  The double space makes
this more apparent, and this is why I say it helps your reader.
5.  I have some students who come to me, and they are used to typing their
papers in a WAD of text.  White space enhances aesthetics and
readibility.  Let's not throw space away.  It serves an important
function.
6.  Michael, you mention another reason:  Automaticity.  Those of us who
learned to type correctly have the double space automaticitized.  That is
a good thing, so leave it alone.  Have your students develop the same good
habit.

Carla Cruzan

> A colleague asked me today if we're still leaving two spaces after
> periods, b oth in running text and within MLA citations.  I seem to
> remember that word-processing has brought about a change in the rule, but
> I can't find anything in the handbooks in my office.  I myself can't stop
> myself from putting two spaces after periods, but that's no guide to the
> current rule.  Can anybody help?
>
>