A is for Apple / A stands for Apple

A is for Apple

Would be the correct common phrase. This is used in nearly every Elementary School in any English speaking country in order to teach the Alphabet to small children. The meaning is pretty basic, namely that “The word ‘Apple’ begins with the letter ‘A’.”

The word used to teach each letter to small children varies for some letters, but is remarkably consistent for others. Every teacher uses “A is for Apple”, for whatever reason. Likewise, C is always for Cat. But B might be Bat, or Boy, or Ball, or a number of different options. D is usually for Dog, but occasionally for Dinosaur (because kids love dinosaurs). E is sometimes Egg, but sometimes Elephant. I don’t know why.

Why “for”? It could be parsed multiple ways. For can indicate purpose. “The purpose of ‘A’ is so that we can write the word ‘Apple'” might be another way to read the sentence. Alternatively, for can indicate substitution. “The letter ‘A’ substitutes for the word ‘Apple’.”