Grammar is not just knowing what the parts of speech are, it's knowing how to use them. When learning how to use the parts, the key word is "Function."
In the grammar section I have written some pages about some of the parts of speech. I've researched each topic and I although I have strived to be accurate, there could be errors or typos. The information is meant for those teaching students up to 12th grade.
The grammar section is not meant to be a full reference and it never will be. I recommend that you invest in a good grammar handbook. Most of the handbooks contain much of the same information, the differences lie in the presentation. The presentation can make understanding grammar concepts difficult or it can produce "ah-ha" moments. Hodges' Harbrace Handbook has been my favorite for years and the presentation is good. BJUP's English Handbook for Christian Schools became my new favorite because of its presentation.
About Grading High School Papers
Your teenage children are getting savvy between the ears and when you grade their papers, "This stinks." will not be an acceptable critical criticism. I'm speaking from experience. Your teens will need to know (demand to know) exactly why it stinks in grammatical detail and "Er, I don't know, it just doesn't seem right " doesn't work either. Homeschool teacher, you know what that means.
I recommend this book. It is called English Handbook for Christian Schools. I love this book so much that I bothered to upload an image for it a couple of years ago. Look at the name under the image at Amazon, Donna Young, that's me. You can pay full price for the book or buy a used one for a few dollars. I have two copies of the book and I used the books for my children's high school grammar in conjunction with Jensen's Format Writing. Maybe someday I'll write about that.
Grammar Related Curriculum
As you know, there more choices than the books listed below. These are the books that I used.
Daily Grams (2nd-4th)
Planning Easy Grammar
BJU English Writing and Grammar
I assigned Grammar lessons from the book English Handbook for Christian Schools. Sometimes the assignments were based on my children's grammatical errors in their essays.
Reference Books That I Used Most Often
The three books that I used the most for grammar and composition classes are the three pictured below - BJUP English Handbook for Christian Schools, Hodges Harbrace Handbook, and The Elements of Style by Strunk and White. I used them the most because they are not for any grade in particular, they span years of English grammar and composition. Out of the three, I used BJUP English Handbook the most because it has both exercises and answers.
Hodges' Harbrace College Handbook by Hodges and Whitten, published by Harcourt, Brace, and Jovanovich (an excellent handbook) These can often be found at your public library and used book stores. The older editions are good so if you can find a used one for free or under $10, get it. [I have two, published in 1963 and 1984]
English Handbook for Christian Schools For high school, I used two copies of this book, one for me and one for my student. This book is out of print, but used copies are still available and cheaply priced (as of this writing- 2/2010.) I like this book because it is organized, it has problems sets, and the answers are in the back of the book.
Everyone knows about The Elements of Style? It is an old book; it has been edited; and it has been published many times. An earlier version is online as a free ebook, which is okay and all except that the free ebook does not have the new part.