Hi Lori,
I would suggest using the database or dataform activities. Database is built in, Dataform is a very similar addon with more capability. There would not be any need for students to download anything. Their writing would take place right in Moodle. Both database and dataform will let you create templates of how you want your document to look, and can be viewed as a list or one at a time. The parts of the workbook you don't want them to change would just be part of the template design and the areas you want them to type into would be the database fields you create and position on the template for them to type into.
Both database and dataform also tie into the gradebook system of Moodle if you want to grade the students work. Another advantage is that you can control whether or not student writing/entries are viewable by other students.
Hope this helps,
AL