Book 1 focuses on the basics of punctuation and capitalization; Book 2 assumes he knows those and builds from there. A few of the lessons are review, but most focus on learning the parts of speech. So if he knows the basics of punctuation and capitalization, you should be able to start with Book 2. If you download the free sample of the teacher books, you’ll see a list of all the concepts covered in each book. That list might help you know which book would fit best.
I would highly recommend the teacher book. It contains all the answers, but it also contains rubrics and teaching helps to guide you in assigning and evaluating his written narrations in other subjects, like history and Bible. You’ll see more about that in the sample too.
The main language arts resources recommended for grade 5 would be
- Spelling Wisdom
- Using Language Well
- A typing program of your choice
Those would be for individual work. The family work of poetry and Shakespeare and literature would also count for language arts.
This chart on the SCM Curriculum Guide might help too.