6 1/2 is a little young for grammar and comp.
You should be working with a junior reader that has pictures and simple lines of text and let his see the words in action.
Then maybe work on him doing stick figure comic book pictures of his own using simple lines of text for dialog or action.
Sounds like trying to run before you can walk.
We used flash cards and words on a peg board through most of 1st grade and then got into the old Dick and Jane reading books.
Third grade is when we started writing essays and book reports and doing more complex things.
We also had Sentence Diagraming.
He probably doesn't even understand sentence structure yet.
You have to get into subject, noun, modifier, connecting words.
You're trying to do this like high school Spanish and that often leaves kids in the dust.
You need to get photographs or pictures and show how the words work.
A picture of a boy running
John is running.
Then you get into JOHN, the boys name, a noun, which describes a person, place of thing. In this case JOHN is a person.
IS is a connecting word that goes back to JOHN.
Running is an action word. In this case it means running, like running around the room.
John IS running
The IS refers back to John to show what he is doinging.
Now you can go to a picture of a girl sitting and
Sue is sitting.
You soon learn with simple sentences are and how they are constructed.
Then you get pictures with no words and let him make up the words based on what he has learned and TRY not to be negative.
If there are two boys running and he makes up names and syas
Bob and Jim is running
You don't fault him.
He correct him
IS only applies to ONE person. If it was just Bob running it would be correct.
But with more than one we use ARE
Bob and Jim ARE running.
When it gets too much for him you have to stop, let him absorbe it and master it before going on.
You're trying to get him to do Caculus problems before he has adqueately learned numbers.
This is how education fails.
And you're falling into the same trap.
Don't go over his head.
The way you are currently doing it is not bad, but I don't think he's "seeing" words and sentences, he's just transcribing your work.
That will ROTE him, but he won't have an understanding, just a memorization.
You are programming a computer, not letting the machine discover and learn through experience.