as plural –s. Affixes with more than one meaning are more difficult to acquire, e.g., –s functions both as plural noun and singular third. As it comes to word formation processes such as derivation and compounding, the earliest derivational suffixes to show up in children's speech are those they hear adults use most frequently. (-er as the *'doer' of the action such as walker.) When it comes to compounds, children first make up names for agents and instruments that they don't know by a pattern (N-N), though some of them do not follow the pattern (*cutter grass for grass cutter). Then, they might have the right structure but the words are inappropriate since English already has words with the intended meaning such as car-smoke = exhaust. This process points to a preference for building words from other words, thus place less demand on memory than learning an entirely new word for each concept. Grammatical development Grammar describes the way sentences of a language are constructed, which includes both syntax and morphology. Syntactic development and morphological development Syntactic development involves the ways that various morphemes are ordered or combined in sentences. Morphemes, which are basic units of meaning in language, get added as children learn to produce simple sentences and become more precise speakers. Morphemes can be whole words (like "happy") or parts of words that change meaning of words ("un"happy). Brown proposed a stage model that describes the various types of morphological structures that are developed in English and the age range within which they are normally acquired. Stage I: From 15–30 months, children start using telegraphic speech, which are two word combinations, for example 'wet diaper'. Brown (1973) observed that 75% of children's two-word utterances could be summarized in the existence of 11 semantic relations: Attributive: 'Big house' Agent-action: 'Daddy hit' Action-object: 'Hit ball' Agent-object: 'Daddy ball' Nominative: 'That ball' Demonstrative: 'There ball' Recurrence: 'More ball' Non-existence: 'All-gone ball' Possessive: 'Daddy chair' Entity + Locative: 'book table' Action + Locative: 'go store' Stage II: At around 28–36 months, children begin to engage in the production of simple sentences, usually 3 word sentences. These simple sentences follow syntactic rules and are refined gradually as development continues. The morphological developments seen in this age range include use of present progressive (-ing endings), the prepositions "in" and "on", and regular plurals (-s endings). Stage III: Around 36–42 months, children continue to add