Knees and ankles...I mean niece and uncle

My 9-year-old niece just told me that she sprained her ankle. "Yes. You told me" I said. "Did you still sprain it?" I asked (playing around with the telic sense of the word--she didn't catch that and it wasn't that funny anyway).

"How long ago did you sprain it?" I asked.

"Two days ago" she said. Then she corrected herself. "Well...one and a half day ago."

"One and a half day ago?" I asked thinking she had misspoken.

"Yes" she assured me. "One and a half day ago."