Rationale for the Study

1.1Rationale for the Study

Vocabulary has a very crucial role in language acquisition because of two major reasons. Firstly, without good vocabulary knowledge, meaningful communication cannot occur because communication competence depends heavily on vocabulary (McCarthy, 1990). This idea is also expressed by Wilkin (1972, cited in Shehata, 2008, p.13) who stated that "without grammar very little can be conveyed, without vocabulary nothing can be conveyed". Harmer (1992) also maintains that "if language structures are created from the skeleton of language, the vital organs and the flesh will then be provided by vocabulary".

Secondly, vocabulary has been recognized as a central element in language learning from the beginning stages (Celce-Murcia & Rosensweig, 1989). Centre of Excellence for Early Childhood Development (2010) classifies language development of children into three stages: listening to sounds, collecting words and then producing sentences. Vocabulary knowledge, thus, can determine the quality of language learners' performances because learners who possess big vocabulary size will be more likely to perform the four language skills (listening, speaking, reading, and writing). For this reason, it is essential to build up a large vocabulary repertoire at the early stage of children language acquisition.

For Nation (1990), vocabulary knowledge is commonly defined as knowing a word and knowing how it is used by learners. Knowing a word, however, is not as simple as knowing its forms and meanings. Nation posited that knowing a word mean knowing its written and spoken form, its conceptual and associative meaning, its function, as well as its grammatical and collocation behavior. Nation also categorizes vocabulary knowledge into two categories in terms of its uses: receptive and productive. Receptive vocabulary knowledge refers to the ability to recognize a word during reading or listening activities whereas productive knowledge refers to the ability to produce a word in the form of writing or speaking. Unfortunately, some of these types such as word form and word meaning received great attention while other important aspects such as collocation (or use) are rarely mentioned in teaching contexts. (Hodne, 2009).

Within the area of vocabulary, researchers have emphasized the importance of word combinations, also known as collocation. Collocation is a pair or group of words that are often used together or commonly found together and it is believed that collocations are naturally used by native speakers (Lewis, 2000). For example, in English, one can say "chase the bus" but not "miss the bus", "Make a mistake" but not "do a mistake" and "slump dramatically" but not "slump gracefully" (Lewis, 1997). The ability to predict collocability is part of a native speaker's collocational competence as they develop knowledge of collocation through repeated exposure to the language (Miyakoshi, 2000). The automation of collocations helps native speakers to fluently express themselves since it provides 'chunks' of English that are ready to use. The use of collocation is an important aspect for ESL/EFL learners to sound more native-like (Brown, 1974; Nattinger, 1980 & Lewis 1997; 2001) and to be more fluent (Wray, 2000 & Nation, 2001). Van der wouden (1997) argues that in order to speak English naturally, learners need to be familiar with collocations because the wrong use of collocations, although it can be understood, it does not sound natural.

Based on Benson, Benson, and Ilson (1986), there are two major categories of collocations: grammatical collocations and lexical collocations. Grammatical collocation is "a phrase consisting of combination of a noun, adjective, or verb with a preposition or grammatical structure such as an infinitive or clause. It consists of 8 subtypes as follows: noun-preposition, noun-to infinitive, noun-that clause, preposition-noun, adjective-preposition, adjective-to-infinitive, adjective-that clause, and verb patterns. Lexical collocation is a group of content words that co-occur frequently. There are 7 subtypes of lexical collocations as follows: verb-noun, adjective-noun, noun-noun, noun-verb, noun-of-noun, adverb-adjective, and verb-adverb.

The amount of exposure is a key component of the acquisition of collocational knowledge (Gyllstad, 2007). However, this is not an easy task for EFL learners, as shown in the Marton's