Click Here for Journeys Reading Resources, grades K - 6 (e-textbooks, leveled readers, writing handbooks, reading comprehension worksheets)
These Harcourt PDF workbooks are free to download:
Grade 1 Reading Practice: ebook with printable pages
Grade 6 Grammar Practice (Teacher's Edition)
Grade 6 Reading Practice (Teacher's Edition)
Grade 6 Spelling Practice (Teacher's Edition)
Grade 6 Assessments: This one, by Glencoe, includes pages for reading comprehension, spelling, vocabulary, and writing.
Free grammar lesson videos can be viewed at: Harcourt Grammar Snap Grades 1 - 6