All vocabulary can be either core or context (or fringe) vocabulary.
Core vocabulary is a small set of simple words, that are the most frequently used words and used across all contexts. They constitute more than 80% of the words used in our normal day-to-day communication. Core With just around 100 core words, a person can communicate more than 80% of what is needed. They can be taught and reinforced through a variety of activities.
E.g. In the sentence "I want to eat an ice-cream" - all the words except "ice-cream" are core words. The word ice-cream is a Context word, that is used in a specific contexts only. The remaining words can be used across multiple contexts.
Core words - I, want, to, eat, an
Context word - ice-cream
Another example: They are playing in the park.
Core words - they, are, playing, in, the
Context words - they, are, playing, in, the
Core words can be used across all contexts and are the building blocks of communication and at the heart of language development. It includes all parts of speech except nouns. Nouns are included in Context vocabulary or Fringe vocabulary. Fringe words are used only in specific contexts and are used less frequently. Most Core words are usually short words and consist of verbs, adjectives, adverbs, pronouns, conjunctions, interjections and are less likely to be nouns.
Core can be used across all contexts whereas Fringe vocabulary is context-specific. Core words also give scope for quick and easy 2-word combinations and 3-word simple sentences. Even a beginning communicator can use these few words to make simple phrases using just core words, like "get that," "go up," "stop that," "turn that up," "turn off", "that mine," "get that down” etc.
Why are core words important?
Core vocabulary is powerful because it allows communicators to express a wide variety of concepts and thoughts with a very small number of words. This is because the same core words can be used across multiple contexts and have multiple meanings. E.g. turn around, turn the tap, turn the page, my turn / your turn (turn taking) etc.
Research has shown that about 50 words make up around 40-50% of our daily communication; 100 words make up 60%, and 200-400 words make up 80% of the words we use everyday. Hence easy access to Core words is extremely important in an AAC system.
Suggested Core Vocabulary
There are several suggested lists of Core words. Here is a list of Universal Core - containing a set of 36 important core words to begin with, as recommended by Project Core.
Universal Core vocabulary
FAQ: How to teach Core words?
Source : Internet
Core words dominate everyday speech for toddlers (Banajee, 2003), preschoolers (Marvin, Beukelman & Bilyeu, 1994), adults (Balandin & Iacono, 1999), and seniors (Stuart & Beukelman, 1997).
Core Vocabulary and AAC performance report