Answer:
Walter is referring to a sibling he has who can help work in the fields.
Explanation:
This excerpt is from "To Kill a Mocking Bird," a novel by author Harper Lee published in 1960. The narrator is Scout, a young girl living in Alabama in the 1930's.
In the passage we are analyzing here, Scout has brought Walter Cunningham home. He is a boy from her school who has not passed first grade. Walter explains to Atticus, Scout's father, reason why he has not passed it yet:
"Reason why I can't pass the first grade, Mr. Finch, is I've had to stay over ever' spring an' help Papa with the choppin', but there's another'n at the house now that's filed size."
What does he mean when he says there is another one that is field size? Walter means there is another child, a sibling of his, who can now help as well. "Field size" means the child is now big and old enough to help out in the fields. While he says that, Walter devours the dinner he is served at Scout's house. Helping in the fields is not the only reason why he cannot pass the grade. Walter is poor and malnourished. He has no lunch to bring to school, nor does he have any money to buy the lunch sold there.
