Hannah Estes said she was waiting in line with her family for the Primeval Whirl at the park's Animal Kingdom when she saw a sign counting down to the ride read "one seconds," WESH-TV, Orlando, Fla., reported Wednesday.
"Because I learned in Ms. Bennett's class that a singular number can't be with a plural word, and so that's what it was, and it wasn't right," Hannah said.
Hannah's mother, Teri Estes, said her daughter took a picture of the sign with her "little pink princess camera."
The girl then mailed the picture to Disney officials, who responded with a letter saying the mistake would be corrected soon.
The report did not give the girl's age or hometown.