Intense grammar instruction starting in grade 4, including diagramming, memory work, and parsing sentences. We repeat the same material for three years, diving deeper as the child understands more and more.
Diagramming is easy and fun. Kids love it. Only adults hate it. If you never act like its hard, they won’t either. ?
Analytical Granmar is the closest curricula to what we use, but not as good (in my opinion.) We use Essentials of the English Language through Classical Coversations. Clasdical and CM line up exactly on grammar instruction- short, intense, starting around age 10.