Final answer:
The question refers to the novel 'Insignificant Events in the Life of a Cactus', where Aven Green moves to Arizona in the eighth grade. However, without context, the grade cannot be accurately determined.
Step-by-step explanation:
The question What grade was Aven in when she moved to Arizona? does not specify a particular grade because it lacks context about Aven's story. Typically, this query would come up in the context of a book or narrative where the character Aven is featured. In the novel Insignificant Events in the Life of a Cactus by Dusti Bowling, Aven Green, the protagonist, moves to Arizona when she starts the eighth grade. However, without the context of a specific narrative or more information, it's impossible to provide a precise answer to this question.