When a child is learning how to speak they must learn the different components of language. Language is divided into three parts. Content, Form and Use.
CONTENT
Content of language refers to the semantics of words or what words mean. This is the first component that is learned by a child. It includes vocabulary and it's associated object or action. A child can only really learn the word "car" by understanding that when they hear the sound waves that produces "car" it is a symbol for item itself. This is why the more concrete words (nouns) are usually learned first followed by actions (verbs) and finally the more abstract words (adjectives, adverbs, prepositions, etc.). When measuring a child's language content ability one would look at vocabulary skills and how well the words are understood, used and described by the child.
FORM
Form of language is similar to what we call grammar. This includes word order, verb use, article (the, a, an) use, plurals, pronouns, etc. This is a skill that is formed as a child advances on to complex language and sentences are being formed. The form of language (especially in English) can be difficult. There are so many rules and then so many exceptions to those rules. When measuring a child's language form ability one would take a language sample and determine which rules have been learning, which rules are developing and which rules have not yet understood by the child.
USE
Use of language is the pragmatics of language or the social use of language. These are rules of how language is used or the social rules of language. This includes; turn taking, initiating topics, maintaining topics, body language, greetings/saluations, small talk, etc. This is often one of the biggest obstacles for children on the autism spectrum. Higher functioning children with autism often struggle the most with understanding the use of language. This is why even when standardize language test scores can be approaching or within the average range the language skills are still lacking. When measuring a child's language use ability one would take a language sample and determine which pragmatic rules are understood and which are not.
