Some previous studies (Hill & Laufer, 2003; Mondria, 2003; Sonbul & Schmitt, 2010) validated that the combination of implicit/incidental learning and Explicit/intentional learning is superior to implicit/incidental vocabulary learning alone.

2.3 Teaching vocabulary in isolation or in context

Teaching vocabulary in context means presenting new L2 target words in an example sentence or sentences; teaching vocabulary in isolation means letting learners engage in paired-associate learning or word-list learning in which L1 equivalents are attached to L2 target words. Nowadays, the latter technique is unpopular because just remembering a large number of words without context can be boring, and therefore it may be a challenge to make it a pleasant activity for learners (Folse, 2004). 

2.4 Word- formation

Dealing with word formation involves the idea of “word family”. According to Bauer and Nation (1993), “a word family consists of a base word and all its derived and inflected forms that can be understood by a learner without having to learn each form separately”. A group of words that a learner considers to be a part of one word family will grow as the learner becomes more proficient and incorporates other words into the group (Nation, 2001). 

Many researchers have emphasized the significance of explicit teaching of word formation processes to ELL students. Birch (2007) suggested that English Language Learners should learn morphemes and rules that govern word formation through direct instruction and extensive reading as well as controlled and guided practice with clear examples and sample sentences. Nation (2001) also stressed intentional teaching of word formation processes in English to ELL students, although he cautioned that it may take a long time. Schmitt and Boyd Zimmerman (2002) gave advice to teachers that they’d better provide obvious instruction in word formation and avoid assumption that learners will find and absorb the derivative forms of a word family automatically from exposure. Educational researchers have also given their contribution to approaches and best practices in teaching word formation.

Some researchers have proposed grouping English prefixes and suffixes to facilitate learning and define possible constraints on affix acquisition. They have also advocated teaching one word formation process before introducing another. In order to make teaching and learning of English prefixes and suffixes more systematic, Bauer and Nation (1993) organized them into a series of levels based on their productivity, frequency, regularity, and predictability and stated that this classification might provide “a consistent description of what should be considered to be part of a word family for readers at different levels of morphological awareness”. Schmitt and Boyd Zimmerman (2002) noted that since English inflectional suffixes are regular and predictable, they are likely to be more easily acquired, and so the emphasis in language instruction for ELL students should be placed on derivational suffixes as the rules to create derived forms of words in English are not always straightforward, and language learners might have trouble with identifying them (Schmitt & Boyd Zimmerman, 2002). Language teachers should also keep in mind that “many complex words are not based on regular, frequent patterns and are best learned as unanalyzed wholes” (Nation, 2001, p. 274).

Another way to reinforce derivational morphology among ELL students is to provide them with appropriate language input through reading. Schmitt and Boyd Zimmerman (2002) suggested using academic texts to help ELL students learn derivational affixes. These texts are usually rich in morphologically complex words, and so they might give language learners exposure to a variety of derivational suffixes. But this suggestion may be useful for advanced second language learners, not the beginners.

There has also been a movement in the area of teaching morphological processes to introduce new vocabulary items in conjunction with other members of their word families rather than teaching words in isolation. Bauer and Nation (1993) proposed introducing new vocabulary items along with their derived forms, and suggested that “teaching govern and then briefly pointing out the possibilities of governor, government, and ungovernable is much less work than teaching each of these as a separate item” (p. 264). Schmitt (2000) agreed with using this technique and stated that with this strategy, teachers can “maximize vocabulary learning” and get students accustomed to discussing word derivations on a regular basis (p. 148).  词汇教学策略及延伸课外词汇拓展案例的研究(5):http://www.youerw.com/yingyu/lunwen_55110.html