Portia, apparently unbeknownst to you, this is exactly what the research supports as the key skill for developing solid decoding skills. Once kids have a sense that words are made of phonemes, and can segment those sounds, the next critical step is to learn phoneme manipulation, such as what you were doing with substituting initial or final consonants, and changing the medial vowel sound. That doesn't even require letter knowledge or sound-symbol correspondence. If you have the core phonological processing skills, it is pretty simple to learn reading once someone tells you which letters go with which phonemes.
And yes, there is a developmental coincidence between when kids can learn the necessary phonological processing skills and when we traditionally teach them to read. I just heard a research presentation recently with some preschoolers where they noted that the phoneme segmentation exercise they were testing as an intervention was quite effective, in only a few sessions, but only with the older preschoolers (4 yo). These were NT kids, of course.
I would work on oral PP skills first, while continuing to read aloud lots, and start with graphemes (visual representations of phonemes) once the oral phoneme manipulation is fluent. This has the advantage also of sounding silly and fun to most preschoolers. (Saying words backwards, learning pig Latin, changing words into other words, etc.)
Oh, and I also taught mine to read only by personal request. Earlier for the phonics kid, and at K age for the visual learner.
Last edited by aeh; 05/23/14 08:04 PM.