Mary noted that she will be developing her own
additional  materials for sentence diagramming. I hope
those of you who do use diagramming eventually have
students select the sentences to be diagrammed,
sentences from their own writing (or reading).
     I devote about three weeks to sentence structure in
my college Freshman comp classes. My approach is
somewhat different from traditional diagramming. I
have students begin by learning to identify
prepositional phrases in entire paragraphs. Then we
add subject/verb/complement patterns. Then we add
clauses (subordinate and main).
     This leads to the students' evaluating a passage of
their own writing, which they then evaluate statistically
for such things as words and subordinate clauses per
main clause. As we discuss the implications of these
statistics, students are often frustrated that they were
not taught this stuff in high school. (They could have
been; I would even say should have been.) Among
other things, we discuss "norms": the average
professional uses 20 words per main clause. (Rough
norms for school students are in the research of
Kellogg Hunt, Roy O'Donnell, and Walter Loban, and I
have been slowly working to futher validate and
supplement their work.) When a student who is writing
nine words per main clause sees that the class
average is 15 and that some classmates are writing
19 or more, the student begins to understand that
his/her writing sounds "different."
    Many students want me to spend more time on
syntax in the course, but I can't do so in Freshman
comp. Naturally I prefer my approach rather than
sentence-diagramming, but next to my approach,
diagramming is the best thing students can do.