This advice-column-style blog for SLPs was authored by Pam Marshalla from 2006 to 2015, the archives of which can be explored here. Use the extensive keywords list found in the right-hand column (on mobile: at the bottom of the page) to browse specific topics, or use the search feature to locate specific words or phrases throughout the entire blog.
I see the addition of a schwa as the child’s way of making a simpler speech motor pattern. According to researchers, the CV is the simplest motor pattern and kids change a CVC to a CV-CV to make it easier.
All kids do this — e.g., “mom” changes to “mama” and “dad” changes to “dada”. They also do this with the diminutive — “dog” changes to “doggie” and Cat” changes to “kitty.”
Adding the schwa is a strategy to help them learn to put final consonants on the ends of words. I actually TEACH my clients to add a schwa and to use the diminutive before I teach them final consonants! 😀