"Four" doesn't exist. Caitlyn counts the corners on the breakfast table: "One corner. Two corner. Three corners. Five corners." Same thing when she's counting pancakes on the griddle: "One pancake. Two pancake. Three pancakes. Five pancakes." This afternoon, she was counting books: "One two three five six seven eight nine, seven eight nine."
Just to be sure, I asked her to say "four": "Caitlyn, can you say 'four'?" She looks at me, tucks her chin, and says, "Five".