All children acquire speech and language skills in a universal way, meaning they typically master specific skills in a well-defined sequence. For example, typically-developing children start speaking with one word utterances between 10 and 14 months of age, with two-word utterances usually appearing at about 24 months of age. Knowing the entire sequence of typical speech and language acquisition enables the speech language pathologist to diagnose children who are not developing language skills appropriate for their chronological age. In order to quantify this, a speech language pathologist will use standardized tests to compare a child’s language skills with his or her age-matched peers. The purpose of standardized testing is not only to objectively measure a child’s level of speech and language development but also to establish an inventory, or listing of his or her skills. The speech language pathologist will also use informal measures, such as observation and interactive play to further define an individual’s speech and language development.