The methods I know of for teaching notation are: a) positional method, where the child effectively plays only a very limited number of notes for quite some time, and learns to associate the written notes with the notes played by repetition of only that limited series of notes. Lots of the commercially available beginner books use this method - Alfred's is the one I'm most familiar with. With this method, the separate skills of playing the piano and learning to read, aren't divorced from each other.b) staff method, where the child learns all the notes on the stave, usually by some sort of mnemonic (Every Good Boy Deserves Fun)