What's the difference?
Let's take a common conversation between a mom and child.
Mom: "What do you want to eat?"
Child: "I don't know."
Mom: "Do you want string cheese or yogurt?"
Child: "I want string cheese."
There are a total of 20 words in this conversation. 15 of those words are core words (want, do, don't, I, you). The other 5 are fringe words (string cheese, yogurt).
Core words: Account for 75-80% of the words we use everyday, they are high frequency. They can be used repeatedly for a variety of conversations in many different settings. Most of the core words are pronouns, verbs, determiners, adverbs, adjectives and prepositions. These words are often more difficult to visualize. That's because there isn't really a picture or object that represents words like "want", or " put."
Fringe words are more specific to a topic, environment or individual. They account for about 20-25% of our vocabulary. They are not generic words and can not be used across many different environments. In our conversation example, the fringe word "string cheese" can not be used in a variety of different environments and topics.
In therapy, fringe words are often easier to teach because you can picture the item or hold up an object (ball, car, horse, puzzle), however core words are the main words and are more flexible to use across environments and communication partners. Since we don't speak using only fringe vocabulary, it is imperative that we focus on teaching core words even though it can be challenging.