Reading news for informationHow much vocabulary a CFL l：阅读informationhow多词汇CFL L新闻.ppt

Reading news for information:How much vocabulary a CFL learner should know 笪 骏 Middle Tennessee State University jda@ Outline Reading and vocabulary size Estimates on Chinese vocabulary My research Remaining issues 1. Reading and vocabulary size Past research indicates that vocabulary knowledge is the single most important factor contributing to reading comprehension (c.f., for example, Laflamme 1997). 1.1 Reading and vocabulary size: Native speakers Number of words that a native speaker knows Educated native English speakers know about 16,000 to 20,000 word families (Goulden, Nation and Read, 1990; Zechmeister, Chronis, Cull, D’Anna and Healy, 1995), where a word family is defined as a headword, its inflected forms and its closely related derived forms (from affixation, etc.) (Nation 2001). Number of words necessary for adequate reading comprehension (Carver 1994) Easy reading: 0% Difficult reading: 2% Appropriate reading: 1% Those observations suggest that 99% coverage rate is needed for pleasure reading of difficult materials. 1.2 Reading and vocabulary size: Non-native speakers Number of words that a non-native needs to know 3,000 word families for general English Laufer (1992) Hirsh and Nation (1992), Nation and Waring (1997) put the number between 3000 and 5,000 word families Coverage rate for pleasant comprehension Liu and Nation (1985) and Laufer (1989) suggested a level of 95% for adequate reading comprehension. Hu and Nation (2000) found that unless there is at least 98% or higher coverage rate of the running words in a text, the probability of successful guessing of unknown words will be severely reduced. 2. Estimates on Chinese vocabulary Our knowledge about similar issues in Chinese is less conclusive. For example, while we have some idea about the number of characters that an educated native speaker knows, we are much less clear about the vocabulary size of native speakers. 2.1 Estimates on Chinese vocabulary: Precompiled lists Estimates on v