I think that the math on this test would have been easier for a bright fourth grader than the language.
Some of those language concepts are difficult for anyone. I don’t know any fourth graders who would grasp the idea that an adjective can sometimes be a noun in that sentence that had to be diagramed.
The plural of “me” is doubtless supposed to be “us.” From a more strictly philosophical point of view it would be “me’s.” (e.g.: There are two me’s, the evil me and the good me.)