If you like creative writing, this is the book to use for beginning writing! Marjorie Frank combines fantastic creative ideas with instruction in the writing process. Each lesson is laid out step-by-step so that it is ideal for the novice teacher yet helpful for the experienced. Children can begin some of the lessons in the Primary Grades book as soon as they can write, although I think second grade level (when children are able to write and spell a fairly large number of words) is the best time to start that book.
Lessons in the Primary Grades are appropriate for children through third and fourth grades (and possibly beyond). Thirty lessons focus on many different aspects of writing, including sentences, paragraphs, questions, poetry, definitions, metaphors, recipes, letters, characterization, riddles, advertisements, conversations, and stories. The writing process is clearly explained at the beginning of the book then reflected in each lesson outline.
Children generally enjoy the lesson themes, which are silly and sometimes nonsensical. Since these books are written for the secular classroom, you might have to do a little adapting to fit the home school situation.
Student activity pages are reproducible so one book per family is all you will need. This approach requires interaction between student and teacher and is even more effective when more than one student is involved.
For older children, see the review of Complete Writing Lessons for the Middle Grades. It is very similar but at a more challenging level of difficulty.