Children often have a very hard time figuring out how to blend sounds together to make words like “cat” and “sat.” Knowing the linguistic principle that a “continuant” phoneme like “s” can be held on to as long as it takes for the child to add the rime (such as “at”) makes teaching the concept of blending a lot easier for child and teacher. Thus, if you want to teach blending, “sat” and “rat” make early blending more manageable than the proverbial “cat.”
Whoa.
