READING VOCABULARY THRESHOLD OF ENGLISH FOR ETHIOPIA TEXTBOOKS AND STUDENTS’ RECEPTIVE VOCABULARY KNOWLEDGE

This study is a corpus-based evaluation of reading sections in English for Ethiopia textbooks grades 9-12 and the receptive vocabulary knowledge of students who used the textbooks. The study evaluated reading threshold vocabulary knowledge of the textbooks. The study also examined if students‟ vocabulary knowledge is sufficient for independent reading. The methodology adopted for this research project is a corpus-based research methodology. It involved compilation and analysis of textbook corpus using computer software. For its framework of analysis BNC, high-frequency word list, and RANGE vocabulary profiling software were used. Receptive vocabulary knowledge of students was measured using The Vocabulary Size Test. The test was administered to 107 grade 12 students of Bahir Dar Preparatory and Secondary School. The result from the study indicated reading vocabulary threshold at 95% and 98% text coverage was knowledge of 4000-7000-word families. The vocabulary size test finding showed receptive vocabulary size of students was 3096-word families, which is below independent reading level. Based on the findings it was concluded that the reading sections need some modification aimed at easing the difficulty. Finally, it was recommended that teachers and students should be informed of

This study is a corpus-based evaluation of reading sections in English for Ethiopia textbooks grades 9-12 and the receptive vocabulary knowledge of students who used the textbooks. The study evaluated reading threshold vocabulary knowledge of the textbooks. The study also examined if students" vocabulary knowledge is sufficient for independent reading. The methodology adopted for this research project is a corpus-based research methodology. It involved compilation and analysis of textbook corpus using computer software. For its framework of analysis BNC, high-frequency word list, and RANGE vocabulary profiling software were used. Receptive vocabulary knowledge of students was measured using The Vocabulary Size Test. The test was administered to 107 grade 12 students of Bahir Dar Preparatory and Secondary School. The result from the study indicated reading vocabulary threshold at 95% and 98% text coverage was knowledge of 4000-7000-word families. The vocabulary size test finding showed receptive vocabulary size of students was 3096-word families, which is below independent reading level. Based on the findings it was concluded that the reading sections need some modification aimed at easing the difficulty. Finally, it was recommended that teachers and students should be informed of the vocabulary demands and make use of resources from vocabulary research findings to compensate for the difficulty of reading texts.

…………………………………………………………………………………………………….... Introduction:-
Textbooks have an important place in the teaching-learning process in an academic context. Students are dependent on their textbooks to learn a language or other subjects and the ability to read effectively determines students" academic success and future career. This makes the issue of readability and material evaluation a vantage point for research.
To make students better readers, one of the areas that require investigation is the suitability textbooks. Adequate researches are not carried out to evaluate the suitability of EFL textbooks used in Ethiopia. Even the ones available are carried out using classical readability formulas and cloze tests. These methods of evaluation are outdated and no more used widely in use in such studies because contemporary methods and advancement in technology have provided other tools and software for such evaluation. Also, textbook changes make the results from studies ISSN: 2320-5407 Int. J. Adv. Res. 8(05), 905-939 907 The notion "what vocabulary knowledge is" is an area of disagreement among scholars this is due to the existence of different types of definitions. According to Laufer and Paribakht (1998), "No clear and unequivocal consensus exists as to the nature of lexical knowledge". Nation (2001) states knowing a word is the sum of three significant knowledge elements that is the knowledge of form, meaning, and use of the word. For all the three elements there is both a receptive and productive knowledge. For example, if we take Form Spoken language the receptive knowledge refers to knowing what does the word sound like and the productive knowledge is knowing how is the word pronounced?
Henriksen (1999) as cited in (Pignot-Shahov, 2012), lexical knowledge is categorized into three components: partial to precise knowledge, shallow to deep knowledge, and receptive to productive knowledge. lexical knowledge has been construed as a continuum consisting of several levels of knowledge, starting with superficial familiarity with the word and ending with the ability to use the word correctly in free production" (Faerch, Haastrup& Phillipson, 1984;Palmberg, 1987) as cited in (Laufer and Goldstein 2004).
From the above views, the types of it can be seen that full lexical knowledge is the sum of various knowledge dimensions and there is a move from mere recognition to an advanced productive state. Word knowledge is different among individuals some may excel at grammatical aspects of it while others exhibit knowledge of word parts. Acquiring all dimensions is challenging even for native users of the language. Which makes it even harder for students to learn in a foreign language (Schmitt 1995).

Receptive and productive vocabulary:
Receptive knowledge refers to listening and reading while Productive knowledge refers to speaking and writing (Laufer and Goldstein 2004). A reader with Passive or receptive knowledge can listen or read and understand the input. In terms of vocabulary, one can perceive the form of the word and retrieve its meaning or meanings. Whereas in productive knowledge one can produce the right vocabulary in the productive language skills i.e. speaking and writing. Scholars suggest that receptive knowledge should not be regarded as a complete absence of productive elements "listening and reading may not be entirely ""passive"" processes, the terms passive and receptive are often used interchangeably" (Laufer & Goldstein, 2004).
In an inquiry that looked at some factors that affect passive and active vocabulary relationships, the nature of vocabulary development Laufer (1998) found that passive vocabulary is larger than controlled active vocabulary and learners with larger passive or receptive vocabulary control active vocabularies and slightly better free active vocabularies in written expression. Besides, it is stated that while the passive vocabulary develops faster active vocabulary development is slow. In ESL context the development of passive vocabulary requires multiple exposures and considerable opportunities to use (Laufer and Paribakht 1998).

High Mid and Low-frequency Words:
High-frequency words as the name indicate is the list of frequently occurring vocabulary in language use. According to Nation ( Nation, 2011a) "high-frequency words makeup a relatively small, very useful group of words that are important no matter what use is made of the language. Because each word in this group is frequent, the learners will get a very good return for learning them." Most of these words are content words and knowing enough of them allows a good degree of comprehension of a text.
The most widely cited high-frequency words are the first 2000 words families. This classification was based on the classic list of high-frequency words is Michael West's General Service List 1953 ( Nation & Waring, 1997).According to (Schmitt and Schmitt 2014) GSL includes a little over 2,000 headwords and has been an important resource for teachers and material writers for many decades. The 2,000 figure was based on research on oral discourse. Later in a recent study (Nation, 2006) argued that the core vocabulary should include the most frequent 3,000-word families. After this level of 3,000-word families, other opportunities to learn will avail because learners who attained this level can learn from context (Schmitts, 2014). The idea here is that high-frequency words are very useful due to their frequent occurrences in language use and special focus should be given to teaching these words before passing to other vocabulary groups.
The mid-frequency vocabulary covers the range between high and low-frequency vocabulary. To some extent, academic and technical vocabulary can be classified as the mid-frequency range. The mid-frequency vocabulary is 908 essential when operating in English across a range of different topics and situations, for instance, to cope with the university studies in English. (Schmitts, 2014, p. 495).
Nation, (2011) states that the term Low-frequency words refers to words that occur infrequently and are sometimes limited to specific fields of study. When the complete word frequency count is made for a text, it is found that words of high rank, that is of low frequency, occur in such a way that many words have the same frequency (Booth 1967).Nation, (2011) suggests that a significant amount of class time should not be taken to teach these words. Instead, learners should learn them according to their specific needs of these words. Nation claims large number of unknown words in reading material has negative impact on readers" comprehension and vocabulary learning (Nation, 1983).

Vocabulary as a factor of reading:
The Longman dictionaryoflanguage teaching and applied linguistics defines reading as processes by which the meaning of a written text is understood. Anderson et.al also define reading it as "Reading is a process in which information from the text and the knowledge possessed by the reader act together to produce meaning" (Anderson et al. 1985).Another reading scholar Goodman (1967) defines reading in the following terms: Reading is a psycholinguistic guessing game. It involves interaction between thought and language. Efficient reading does not result from precise perception and identification of all elements, but from skill in selecting the fewest, most productive cues necessary to produce guesses which are right the first time. The ability to anticipate, that which has not been seen, of course, is vital in reading. (p. 127) Grabe (2014) also defined reading as "a complex ability to extract, or build, meaning from a text." The above definitions reveal that a conclusive definition for reading is not yet available given the complex nature of reading. Concerning this Grabe (2009) notes that a proper definition of reading will need to account for what fluent readers do when they read, what processes are used by them, and how these processes work together to build a general notion of reading. Granting that no single statement can capture the complexity of reading, (Grabe 2009). Even if a single definition is not available, it is possible to underline the major themes that emerge frequently in defining reading. The guiding ideas that emerge from the definitions are the view of Reading as a process and this process results from negotiation of meaning between the text and its reader and the success of achieving understanding depend on the knowledge, expectations, and strategies a reader uses to uncover textual meaning.
Vocabulary knowledge is considered a major determinant factor for reading and comprehension. Researchers establish this claim substantiated by Research evidence. Adams and Huggins (1985) noted word recognition skill is the major factor that separates good and less skilled readers. The vocabulary of first graders is a significant predictor of reading comprehension ten years later (Cunningham and Stanovich 1997).

Lexical Thresholds for Listening and Reading Comprehension:
Researchers in corpus linguistics have been conducting researches that are targeted to find vocabulary threshold levels and determine the amount lexical knowledge that language learners need for various language needs and the relationship of vocabulary to comprehension (Laufer 1989; Nation and Waring 1997; Webb and Nation 2008; Laufer and Ravenhorst-Kalovski 2010; van Zeeland and Schmitt 2013a). One central element of these studies is the use of frequency lists for research as stated before a small number of vocabulary account for the majority of written and spoken text. It is believed that learners acquire vocabulary in the order of their frequency and range. Nation (2006) states "High-frequency and wide-range words are generally learned before lower-frequency and narrowerrange words". Evidence for this has been provided by researchers Read (1988) and Laufer, Elder, Hill, and Congdon (2004) their findings show that students" scores dropped when there is a move from moved from higher to lower frequency levels.
In their quest to find vocabulary threshold essential for comprehension researchers have asked how much lexical coverage is necessary for listening, reading comprehension. One of the ways to finding this amount is by studying how much vocabulary one needs to know to use it in various circumstances like reading an academic text a newspaper, a novel, or take part in dialogues. The amount of known words in a piece of discourse is referred to as lexical coverage or text coverage (Nation and Waring 1997). Laufer and Ravenhorst-Kalovski (2006) define the term lexical threshold is defined as "the minimal vocabulary that is necessary for "adequate" reading 909 comprehension" and according to Nation it is "How much unknown vocabulary can be tolerated in a text before it interferes with comprehension?" (2006, p. 61).
Lexical coverage is an essential measure, for it allows the calculation of estimates of the vocabulary size necessary for comprehension of written and spoken texts (van Zeeland and Schmitt 2013). Even though majority of the studies conducted in non-native comprehension have mainly focused on reading and used results of such findings as an estimate for listening. Different approaches have been followed to answer the vocabulary threshold question. Two of the approaches used are examining the coverage that words of different frequency levels provide to texts in representative corpora, testing students on text comprehension, and relating different reading scores to learners" vocabulary size. Researches dealing with threshold vocabulary are discussed below in order of their appearance.

Studies on Lexical Thresholds for Listening and Reading Comprehension:
One of the researches in this regard is by (Laufer 1989:198).Laufer"s study was conducted to see the relationship between learners" vocabulary knowledge and comprehension. The study was conducted by giving a reading comprehension test and given a lexical coverage test for 100 first-year University students who are native speakers of Hebrew and Arabic, taking English for academic purposes course. The first test was used to measure their reading comprehension and the latter to see students" vocabulary knowledge. She measured what percentage of word tokens must be understood to ensure reasonable reading comprehension of a text. Laufer found that reading academic materials is significantly affected by lexical knowledge of the text. The finding also showed that knowledge of 95% of the text"s vocabulary was usually required to score 55% on a comprehension test and suggested that 95% of lexical coverage was the lexical threshold. Note that 55% was the passing score at the university the study took place. She stated that when the lexical coverage was below 95% "comprehension was impaired despite the other facilitating factors that might have affected reading". Also, Laufer claimed, it does not mean that comprehension does not occur below the suggested threshold but it will be insufficient "lower lexical coverage will be associated with unsatisfactory more often than with satisfactory comprehension". Laufer recommended that language courses focus should include increasing students" vocabulary capacity, "since many students who begin academic studies possess much small amount of vocabularyand massive vocabulary expansion should be one of the major goals of any course in Language for Academic Purposes" (Laufer, 1989).
Another study by (Hu and Nation 2000)was carried out to investigate the relationship betweentext coverage and reading comprehension for non-native speakers of English with a fiction text.
They measured Reading comprehension testing students on multiple-choice reading comprehension test, and a written cued recall of the text. Before using the tests on non-native speakers, it was trialed with native speakers. To see at what level of coverage comprehension is likely to occur they created four coverage groups at 80%, 90%, 95%, 100%. This was done by changing some text words with non-words so it represents the different coverages. For example, in their text with 80% coverage, 20 out of every 100 words were meaningless words. With a text coverage of 80%, none of the participants gained adequate comprehension. With 90%, a small number of participants gained adequate comprehension, and 95% coverage a few more gained adequate comprehensions, but they were still a small minority. At 100% coverage, most gained adequate comprehension. After applying a regression analysis to the data, the result showed 98% text coverage is the threshold, most learners can get adequate comprehension of a text. In Hu and Nations study adequate comprehension was associated with 71% score on the two reading tests. Agernäs, (2015) argued that the use of written recall test in the study might decrease the validity of the results because the test additionally tests students writing skills. According to Agernäs comparing their multiple-choice tests only would have been a more valid comparison. Nation (2006) investigated what vocabulary size is needed for unassisted comprehension of written and spoken English. In addition to this, his research studied what vocabulary size is required to comprehend different written texts like Novels, newspapers, spoken text. It is stated that unassisted comprehension goal needs 98% coverage of a text because it is assumed that learners do not use dictionaries or get help at all. In the study, Nation prepared fourteen 1,000-word-family lists based on data from the British National Corpus (BNC) which contains 100 million-token corpus made up of 90% written text and 10% spoken text, and. The findings of the study showed that: 1. To read a novel vocabulary of 8,000 to 9,000 words plus proper nouns is required. 2. To read newspapers Vocabulary size of around 8,000 to 9,000 words is required. 3. For Unscripted, spoken English 6,000 to 7,000 word-families are needed to get 98% coverage.

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Nation concluded that assuming 98% text coverage is the threshold for unassisted comprehension then 8,000-9,000 word-family vocabulary is needed for dealing with written text, and 6,000-7,000 families for dealing with spoken text. Also, he noted it is in the first 1,000 words, and in the proper nouns,the highest variation in vocabulary coverage is exhibited because the first 1,000 plus proper nouns cover 78%-81% of written text, and around 85% of spoken text (Nation 2006:59-82).
The study conducted by Laufer and Ravenhorst-Kalovski, (2010) included large number of participants than the other studies discussed in this section. 745 college students from different departments taking a course in English for Academic purposes participated in the study. They studied the relationship between second language learners" vocabulary size, lexical text coverage that their vocabulary provides, and their reading comprehension. They also used Paul Nation (2006) word lists, which has fourteen 1,000-word-family (1k-14k) lists based on data from the British National Corpus. Students Vocabulary size was measured by the Levels Test, lexical coverage with Vocabulary Profile software, and reading comprehension by a standardized national test.
Their findings on what the vocabulary threshold level enables comprehension was similar to Hu and Nation i.e. two coverage levels 98% and 95%. Based on their analysis they also suggested two-threshold coverages 98 % coverage for ideal comprehension and 95% for acceptable comprehension. They indicated 98 percent coverage can be achieved with the knowledge of 8,000-word families including proper nouns and 95 percent coverage can be achieved with the knowledge 4,000-5,000-word families including proper nouns. In terms of the relationship between coverage, vocabulary, and reading they, stated increments of vocabulary knowledge contribute to reading comprehension even though they hardly improve text coverage. The study showed a small increase in lexical coverage from one level to another in the list may be beneficial to reading as a larger increase in coverage. They argued that despite the widely held notion in corpus-based studies, infrequent vocabulary does not provide a good return for the learning effort due to its small text coverage. Less frequent vocabulary adds considerable improvement in reading comprehension. They claimed that the benefit of teaching infrequent vocabulary seems more essential than assumed before(Laufer and Ravenhorst-Kalovski 2010). . Schmitt, Jiang, and Grabe (2011) also studied the relationship between percentage of vocabulary known in a text and level of comprehension of the same text. 661 participants from eight countries completed a vocabulary measure based on words drawn from two texts, read the texts, and then completed a reading comprehension test for each text. The results showed that a relatively linear relationship between the percentage of vocabulary known and the degree of reading comprehension. Their results suggest that the 98% estimate is a more reasonable coverage target for readers of academic texts (Schmitt et al. 2011).
The study by van Zeeland and Schmitt (2013) investigated the lexical coverage of native and non-native students in listening comprehension and explored if there is a difference in the lexical threshold for speaking and reading.76 participants (36 native and 40 non-native speakers) listening comprehension of factual information was tested. Making of the test employed Hu and Nations method of creating different coverage levels by inserting non-words levels of lexical coverage, and measuring participants" comprehension. The finding of the study is summarized below Native speakers" comprehension test 1. With 100 % coverage, nearly all participants achieved the maximum score of 10 2. With 98% coverage, one-third of the participants reached the maximum score 3. No difference in comprehension was observed with 95% and 90 % coverage no difference in comprehension between 95 and 90 percent coverage 4. Non-native speakers 5. With 100 %, coverage 29 out of 40 participants achieved a maximum score of 10 they have lower than the native scores. 6. Non-native participants could still adequately comprehend the passage with 95% and even with 90 % lexical coverage.
Generally, the findings of the study showed that lexical knowledge contributes to listening comprehension both in L1 and in the L2. Most native and non-native participants could adequately comprehend the spoken texts with only 90% coverage, although the non-natives showed considerable variation at this level. At 95% coverage, non-native participants also demonstrated relatively good comprehension, but with much less variation. van Zeeland and Schmitt (2013a:457-479) concluded that there is a difference with the lexical threshold needed for speaking and 911 reading text comprehension. Comprehension for spoken texts can be achieved with much lower coverage than reading comprehension. They argued unless the goal is 100 percent comprehension, 98% is inessentially large coverage and coverage from reading research like (Nation 2006) concluded for good comprehension level 95 % coverage might be sufficient in most cases.
Despite some variation in the studies above, there are similar major themes that can be observed.
First, the studies indicate that there is a strong relationship between vocabulary knowledge and comprehension for L1 and L2 scenarios for both listening and reading comprehension texts. Their relationship is evident because the amount of lexical knowledge one has affected comprehension as shown in the studies. In addition to that, the findings show knowledge of the most frequent vocabulary is the most determinant factor in terms of text coverage and comprehension. This is due to the higher coverage these words have in most written and spoken text.
Higher coverage in vocabulary as stated in the studies leads to higher comprehension returns in tests. Even if vocabulary is not the only determinant factor in achieving understanding it is more likely that students with less vocabulary knowledge can"t successfully make up for it with knowledge of other features leading to comprehension.
One of the other major traits worth mentioning from the research findings is that the difference in threshold vocabulary required for listening and speaking. Despite the fact, higher coverage leads to better comprehension for both skills, listening comprehension can be achieved by less amount of lexical capacity than reading. Since much schoolwork needs a lot of reading of various materials students who aspire to continue their academic journey should aim for larger vocabulary goals. Since much schoolwork needs a lot of reading of various materials. This weighs more truth, especially for EFL and ESL students. One of the reasons is because Non-native or EFL students possess less amount of lexical coverage. Nevertheless, the findings of the studies have shown that EFL learners can reach higher comprehension if they have the lexical knowledge that enables minimal to higher threshold levels. As shown in the above studies and the literature this threshold levels can be reached with a limited number of vocabulary.
Regarding threshold levels, the data from the above studies show there are two suggested threshold levels i.e. the 95% and 98% coverage thresholds. While 95% coverage is the lower threshold level 98% is the upper threshold for a goal of higher comprehension goals. Concerning this the terms used in describing threshold like minimal, reasonable, higher, lower has been a source of debate among researchers. Even in the studies above the researchers have tailored their meanings to the terms. For example, in Laufer (1989), minimal threshold expected was a score of 55 in the comprehension tests. In Ethiopian context, the minimal acceptable score in any given test is half of what the total score is. Thus, measuring learners" threshold and deciding what is considered lower and higher levels depends on what is acceptable in the researchers' or teachers" context. Even if that is the case when the expected score is higher it will need a greater number of vocabulary knowledge.
Finally, it should be noted that the levels and coverage levels suggested are not based on all or nothing cut of points. Rather in the continuum of language learning, the thresholds are the most determinant levels differentiate between higher and acceptable comprehension. As it is mentioned in the studies, less vocabulary coverage will also affect the likelihood of successfully using other reading strategies

School Textbooks Lexical treatment:
School textbooks play a central role in school contexts because texts play a big role in instruction. Dolores & Jiménez, (2010) describe textbooks as "the starting point for the class and the teacher, resource bank for teaching materials and ideas, potential syllabus; and a reference for grammar and vocabulary" (Dolores and Jiménez 2010).
Considering the importance of textbooks, the appropriateness of the books in content, presentation, and overall balance among the four language skills is a major task, which should be treated very seriously. When textbooks are used in EFL context like Ethiopia where supplementary materials are not available textbooks serve even a larger role as a sole source instructional input.
There is an agreement that textbooks should be prepared to fit the context they are used despite the agreement the appropriateness of school textbooks is a source of debate. Hansen, (2009) states that the most pressing and important issues in writing school textbooks are controlling the difficulty and appropriateness of textbooks and crafting the books in a way that facilitates readers' move from simple materials to complicated ones. Meeting these goals is a 912 source of problems for writers and textbook designers (Richard C. Anderson et al., 1985)states "A vexing problem for textbook writers is matching the difficulty level of the material to the ability level of the child for whom the material is intended" (Anderson et al. 1985).
Multiple factors like content selection, topic, presentation, graphics, and layout determine how a given book meets the need of its intended readers. One of the major issues raised regarding textbooks appropriateness is their selection and presentation of vocabulary. Milton (2009) states in selecting vocabulary for textbooks the two major issues are deciding what vocabulary to select for teaching and the other is how the vocabulary content is distributed throughout the book O'Dell 1997 as cited in Milton (2009) notes that the vocabulary aspect of textbooks has not been given the attention it deserves.

Studies conducted on textbooks:
Researchesconducted to evaluate vocabulary selection and load of textbooks showed that vocabulary selection, is not carried out with much attention and there exists a discrepancy among textbooks written for the same grade levels. Milton and Vassiliu (2000) reviewed three beginner textbooks' choice of words and the number of lexical items the textbooks have in common. The books are intended for 100-hour beginner"s course. Their result showed that book one contains 909 types, book two 964 types, and book three 1175 types" words. Even after they removed, personal names and contents not relevant for the study they found out only 328 types are common to all three texts. They stated that the numbers support the previous assumption that EFL learners are exposed to much more vocabulary than needed. Even if textbooks are not supposed to be, identical in their vocabulary selection these many differences at the same level imposes a lot of vocabulary load, which may have a negative effect on the learning of vocabulary items and developing reading skills. Dodigovic (2005) studied lexical items used in global sociology and language courses and compared it with how much vocabulary the students knew from the items presented in the textbooks. They also tried to see the presence of the 3000 high-frequency lexical items in the textbooks. The study was conducted by preparing and analyzing corpus from the textbooks and students' writing for a semester. In their analysis, they found out contained that texts contain 6,559 different vocabulary items and many of the words are low-frequency words and 15% of the words in the textbook"s vocabulary is out of the 3000 most frequent words and academic vocabulary list Range. This is Contrary to what Vocabulary frequency study results show that the most frequent 3000 words plus the academic word list covers more than 90% of any academic text and the AWL alone is estimated to cover 10% of any academic text. The conclusion Dodigovic made about the text was the texts analyzed can be expected to present a difficulty even to a native speaker of English.
The other result from students' writing showed students productive vocabulary is about 600 different word types Nation (1990) suggests that the receptive vocabulary could be estimated to be 2.2 times. Their estimated calculation showed that the receptive vocabulary of students is about 1,320 words and if added up with their productive vocabulary of 600 it will mean that the students have a vocabulary of 2,000 words. Research shows that students should know at least 95% of the words for a moderate comprehension and 98% of the words for higher comprehension results. Thus, the number of words the texts contain and students know suggests students may face strong difficulties in using the books in this study.
One important issue is vocabulary recycling that is students will have a better chance of learning words if there is repeated exposure. Milton (2009) states "writers, if their course books are to be good, will need to consider recycling their lexical vocabulary". For example, a three months long longitudinal case study investigating quality and quantity of encounters of 20 vocabulary items in adult second-language (L2) learners who are taking English for Academic Purposes was conducted by (Joe 2010) showed that frequency of encounters contributes more to vocabulary learning than contextual richness.
Hsu (2011) compiled two corpora of English-medium textbooks for business core courses and business research articles and analyzed how many words are needed for comprehension level of 95%-98% using the BNC HFW. The results show that knowledge of the most frequent 3500-word families and 5000-word families plus proper nouns would provide 95% lexical coverage of a business textbook and a business research article respectively. Business textbooks reached 98% coverage at the 5000-word level while business research articles reached 98% coverage at the 8000-word level (Hsu 2011).

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Similarly, Hsu (2014) studied the vocabulary load of 100 college-level English medium engineering textbooks and from the compiled corpora created Engineering English Word List (EEWL) to cover EFL students" lexical shortage.
The results demonstrate that knowing the most frequent 5000-word families and proper nouns, apparent compounds, and abbreviations would command 95% lexical coverage of an engineering textbook to ensure adequate comprehension. Civil engineering and mechanical engineering, involving 3500-word families necessary for minimally acceptable comprehension, were the least lexically demanding, while marine engineering and biochemical engineering were the most demanding in lexis, stretching to a threshold of 8500-word families. (Hsu  2014b) Kumar LR, (2015) studied the vocabulary presentation of primary school Tamil textbooks prescribed by the Government of Tamil the analysis result showed that there is no gradual increment in the vocabulary across the standards (Kumar LR 2015). A gradual increase in vocabulary is a major requirement in vocabulary acquisition.
Nordlund, (2016) explored if vocabulary in teaching materials corresponds with accepted measures of English highfrequency words. Two same level English teaching coursebooksthatare widely used Sweden are were the focus of analysis. The results showed that variation in vocabulary between books and the textbooks contain a high proportion of one-time and low-frequency words. The result also showed that even though many words do correspond to general high-frequency words, as much as one-third are not found among the 2,000 most frequent English words. Besides, the common words shared by the books occur only once or are of low frequency (Nordlund 2016). If textbooks are intended for the same level such discrepancy is not expected. Torki, (2012) conducted a study exploring seven English as a Foreign Language. Textbooks Used in Algeria in use in these schools to investigate their lexical coverage and readability. The study also compared the textbooks corpora to West's General Service List and Coxhead"s Academic Word List. The result showed that the overall vocabulary contents of the textbooks reflected a level of difficulty inappropriate for the learners using them. Torki concluded that learners" lexical coverage is far from the level advocated by researchers in the field of teaching and learning English as a foreign language. This would certainly make reading comprehension a daunting, if not impossible, task for learners. (Torki 2012) Despite the importance of recycling vocabulary content in textbooks, researchers suggest that it is not given that much focus. Nation (1993) claims that few textbook writers, in reality, do recycle vocabulary systematically. If a textbook vocabulary, presentation introduces too many new items without recycling, and on top of that, if it contains too many low-frequency words students will not be able to learn the words even at receptive level. This, in turn, affects comprehension and learning of content treated in a given text. This should not be confused as if a textbook contains frequent vocabulary and recycles the item learning is insured. As explained in (Richards et al. 2009) "word learning will also be dependent on what thematic material the learner has been exposed to in textbooks and on word difficulty factors such as whether the words encountered are cognate or not. But frequency still has a very powerful effect, probably more powerful than the other factors" (Richards et al. 2009). Thus, textbook writers should consider vocabulary frequency and recycling and balance it with other elements of the syllabus.
Milton (2009) Suggests in beginner textbooks it is use full to present significant amount of most frequent vocabulary in line in sync with content to be taught because Frequency lists are not ordered in theme thus writers should include words among frequency levels and organize them with the themes intended.

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From the above studies, it can be seen that in terms of vocabulary the textbooks do not adhere to the lexical frequency band standards. Even textbooks intended for the same level and same course may contain variations. Another aspect is even when the textbooks neglect the importance of recycling in their presentation of vocabulary. The other point worth mentioning is even approved books by publishers and education entities may not be appropriate in their vocabulary load and presentation. Thus, conducting a corpus-based study of reading materials at various levels is essential. The findings of such research will reveal the difficulty of the textbooks, in addition, the word lists compiled can indicate what vocabulary items to focus on. This in return is useful for both students and teachers. Finally, such research findings are useful to inform what goes in textbooks at the preparation stage before it reaches users.

Methodology:-
The methodology adopted for this research project is a corpus-based research methodology, which involves a compilation and analysis of corpora using computer soft wares. One point that all writers defining corpus linguistics agree upon is that corpus linguistics is empirical, in that it examines, and draws conclusions from, attested language use, rather than intuitions.

Participants of the study:
The study participants are grade 12 students of Bahir Dar Preparatory and Secondary School. In the school, there are six sections grade 12 sections. Section A and B were selected using convenient sampling. The total number of students is 107 of the total number of students 54 students are in section A and section B contains 53 students. Grade 12 is selected because one of the objectives of the study was to measure the receptive vocabulary of students at the end of preparatory school. One of the reasons for this is to find out how many words students know after completing high school and relate their vocabulary knowledge to the vocabulary profile of the textbooks in this study. Since the four textbooks in the study are prescribed for high school and preparatory grades (9-12) students' test scores indicate if their receptive vocabulary enables them to use their textbooks.

Data Collection Instruments:
The primary data sources of this research are English language textbooks used from grades 9-12. To extract clean data three software were used Foxit Phantom PDF Version: 8.3.0.14878, Notepad ++ V 7.8.2, Were used. Also, Nation &Beglar (2007) Vocabulary Size Test is used to test what receptive vocabulary of grade 12 students. Instruments used for data gathering and preparation are discussed below.

Foxit phantom Pdf:
used Foxit Phantom PDF is a software used to view, create, edit, and secure PDF documents. It was used to make the textbooks machine-readable for editing and extracting using its OCR feature. Optical Character Recognition, or OCR, is a software process that enables images or printed text to be translated into machine-readable text. OCR is most commonly used when scanning paper documents to create electronic copies, but can also be performed on existing electronic documents (e.g. PDF). It was also used to remove unwanted content from the textbooks and extract parts of the textbooks needed for the study.

Note pad++:
Notepad++ is a free text editor that comes with a lot of features. For instance, auto-save, syntax highlighting, tab support, multiple views, macros, and much more. If the core functionality is not enough, there are also many plugins available. Notepad++ with the TextFX plugin to quickly remove duplicates, remove blank lines, and sort data in one 915 operation. Notepad++ to quickly insert, edit or delete text in multiple locations in one file at the same time. The software is used to edit the converted text files of the textbooks. The text output from pdf output contained a lot of errors and unwanted text elements using this software the text is cleaned from unwanted textual elements.

The vocabulary size test:
To answer the question, what is the receptive vocabulary size of students"? vocabulary size test developed by Paul nation was administered to students. The Vocabulary Size Test is designed to measure both first language and second language learners" written receptive vocabulary size in English. The test measures knowledge of written word form, the form-meaning connection, and to a smaller degree concept knowledge. The test measures largely decontextualized knowledge of the word although the tested word appears in a single non-defining context in the test. It is measuring written receptive vocabulary knowledge, which is the vocabulary knowledge required for reading. It is not measuring listening vocabulary size, or the vocabulary knowledge needed for speaking and writing. It is also not a measure of reading skill, because although vocabulary size is a critical factor in reading, it is only a part of the reading skill. Because the test is a measure of receptive vocabulary size, a test-takers score provides little indication of how well these words could be used in speaking and writing.

Data Analysis procedures:
The data analysis procedure was tailored according to each research question. The first question was set to measure receptive vocabulary threshold requirement for meeting the target reading vocabulary knowledge threshold of 95% Lower coverage and 98% upper coverage threshold. To achieve the objective reading sections of each textbook was analyzed using RANGE analysis and BNCHFWL was used as a basis of comparison.
The base lists used are 15. Among the lists, 14 of the lists represent the 1000 word lists of High-frequency lists (levels 1k-3K), Midfrequency lists (levels 4k-9k), and low-frequency lists (levels 10K-14K). to run the analysis all proper nouns were added to base list 15. Base list 15 is a list comprising all the common proper nouns around the world. Since this list is not exhaustive list names that are not in the lists but exist in the textbooks were added to this base list. This was done to examine the text coverage of proper nouns in the textbooks.
The final set of research questions focus was the receptive vocabulary knowledge of students and relating their vocabulary knowledge with the required target receptive vocabulary for reading academic texts independently. To answer these questions the following analysis was used. Students' test scores were marked and recorded in an XL spreadsheet for calculations. Test scores were then multiplied by 100 as suggested by the Vocabulary Size Test guidelines to reach the total receptive vocabulary knowledge of each student. The multiplied score represents a student"s receptive vocabulary knowledge of students. The next step in the process is comparing the scores with the target vocabulary knowledge set for different reading purposes. In this case, reading academic texts independently.

The lexical threshold of reading sections
The following table shows the text coverage of the reading passages in the BNC high frequency list. In grade eleven the passages are comprised of 1998-word families in the BNCHFWL 14k list. The range of vocabulary required is 4k-7k including proper nouns for lower and upper threshold coverage respectively. Level four-word families with proper noun cover 95.83%. cumulative coverage at level seven with proper nouns is 98.03%.this is attained with 1685 word families for lower and 1885 words for upper threshold coverage. Thus, the word levels required to read the texts at both levels have decreased in this grade eleven compared to grade ten.
The cumulative vocabulary requirement of grade twelve is attained with 1512 word families for lower threshold coverage and 1649 word families for the upper threshold. The lower threshold with 3k word levels including proper nouns is 97.04%. this coverage is higher than 95% which shows that knowledge of 3k word lists gives a higher coverage and the upper threshold can be achieved with a small number of word families. As a result, at 4k level with proper nouns provide 98.64 coverage which is slightly higher than the upper threshold level. which makes reading sections in this textbook are easier to read and understand than the previous grade. To measure the combined coverage of the textbooks RANGE analysis was carried out on the combined corpus of the passages from the four textbooks. The analysis showed the average receptive vocabulary knowledge demand for Lower and upper threshold coverage, requires students to be familiar with lexical items ranging from 4k-8k levels including proper nouns. Cumulative coverage at 4k level is the stage lower threshold coverage is met, and the coverage at this level with proper nouns is 95.65%. To reach upper threshold cumulative coverage receptive vocabulary knowledge must reach 917 8k level with proper nouns, at this word-level coverage is 98.3%. This can be attained with knowledge of 2825-3604-word families for the two target coverages.

Students Receptive vocabulary Knowledge:
One of the objectives of this study was to measure the receptive vocabulary of students at the end of grade twelve to diagnose the level of receptive vocabulary knowledge they join higher institutions with and also to show where they stand with the vocabulary requirement standards studies propose.
With the above purposes in mind students" receptive vocabulary was measured using the Vocabulary Size Test (VST) developed by Nation, I.S.P. &Beglar, D. (2007). 107 students of Bahir Dar Higher Education and Preparatory Secondary School took the test. Students were tested on levels 1k-10k of BNCHFWL. The table below shows the descriptive statistics on the test scores. Table 3 VST score Descriptive statistics The descriptive statistics showed mean score (M=3096.26) and standard deviation was (S=862.634). The high standard deviation showed that there is substantial difference in students test score. Based on their VST score students were categorized into five categories. The table below shows students' test score and their group. Table 4 Students VST score-based vocabulary grouping Generally, the test result showed that on average students in the study have a receptive vocabulary of 3096.26-word families. the result showed students know a limited amount from the 10000 words.
Half of the students fall in the 1k-3k group and only 13% percent of the students know more than 4000 words. In addition, a closer look at the scores showed that even the High-frequency words are not mastered. Not mastering these high-frequency words is disadvantageous for students because these word levels are foundation vocabulary in various written texts. It should be noted the first 3000 words cover more than 90% of students" textbooks in this study. Thus, most student"s receptive vocabulary knowledge is not enabling for independent reading of simplified texts at higher education level. Let alone un-simplified texts students will not read their grade-level English textbooks at required levels with such limited receptive vocabulary knowledge. Especially the reading sections will be difficult due to higher level receptive vocabulary demand.

Discussion:-Vocabulary coverage and reading thresholds of the textbooks:
The vocabulary requirement of the reading sections of the textbooks on average requires knowledge of 4K-8K word levels for the two threshold levels. This shows that students need more than high-frequency words and need to know mid-frequency vocabulary to meet the 98% coverage. The mid-frequency vocabulary is essential when operating in English across a range of different topics and situations, (Schmitts, 2014, p. 495). The importance of mid-frequency words to reading is similar to other findings of earlier studies. For example, Nation (Nation 2006:59-82)concluded that assuming 98% text coverage is the threshold for unassisted comprehension then 8,000-9,000 word-family is required. Laufer and Ravenhorst-Kalovski (2010) indicated 98 percent coverage can be achieved with the knowledge of 8,000-word families including proper nouns and 95 percent coverage can be achieved with the knowledge 4,000-5,000-word families including proper nouns. Also, Schmitt and Schmitt (2014) argued that even the ability to read with some guidance and support requires 95% of text coverage, which entails knowledge of 4,000 to 5,000-word families. Therefore, even assisted reading requires students to know mid-frequency vocabulary. Thus, 918 it can be stated that the real vocabulary requirements are revealed when reading sections are focused on because the reading sections are the main targets of reading comprehension.

Descriptive
Another aspect of the textbooks worth mentioning is the random nature of vocabulary coverage requirements. For, example grade ten reading sections require 5000k-9000k word levels and grade twelve reading section vocabulary load is 3000k-4000k words for the two threshold levels. This signifies that higher level of vocabulary knowledge is required in the lower grades than the upper grades. Thus, the reading sections do not move from easy to difficult as grade level progresses.
The difference in the range of vocabulary required and the fact that more vocabulary is required at lower grade reading materials than lower level is against vocabulary presentation principles. That is, it is assumed that both native-and non-native-speaking learners acquire vocabulary largely in the order of its range and frequency. High frequency and wide-range words are generally learned before lower-frequency and narrower-range words (Nation, 2006).
One key factor to be noted here is corpus-based studies have shown that even textbooks and reading materials approved by Education authorities and publishers show discrepancies in their vocabulary load and presentation across various metrics. For example, Hsu (2009) examined 20 international General English textbooks, ranging from low intermediate to advanced levels. One of the findings which are similar to this study is that the advanced textbooks required less vocabulary than intermediate textbooks.in the study the textbook Reading for real required 4,000-4,500-word families to reach 95% coverage, while the low intermediate Reading for success 2 required 7,000-7,500 families. The reality is students will possess less vocabulary knowledge at lower grade levels. higher vocabulary knowledge requirement at such levels will impede the teaching-learning of vocabulary.in addition if the textbooks in higher grades contain less vocabulary content than their lower-grade counterparts" students will also lose the chance of encountering such words in upper grades.

Students receptive vocabulary knowledge:
The last aspect targeted for this study was the receptive vocabulary knowledge measured by testing students the vocabulary size test (Nation & Beglar,2007). The participants were 107 twelve graders of Bahir Dar Higher Education and Preparatory Secondary School.Students were measured on their knowledge of 1K-10K word levels which consisted of 100 questions.
The finding showed that the average receptive vocabulary of the students is 3096-word families.
This shows that students possess limited receptive vocabulary even after many hours of vocabulary instruction.
Hours of English language instruction takes from grade one to twelve is 1360 hours. Unfortunately, this finding is similar to many studies conducted in EFL context.
For example, Chinese English major students know 4000 words after 1800-2400 hours of instruction, (Laufer& Nation,1999), Japanese undergraduate students know 1707-word families (Waring,1999), Hebraic students know 3500 words after 1500 hours of instruction (Laufer, 1998). Even if the contexts of the study and results differ such findings show that EFL students fail to grasp the necessary vocabulary after years of instruction and exposure to English language.
Similarly, the students in this study did not grasp sufficient receptive vocabulary that allows meeting different reading needs. For example, Nation (2006) states 8000-word families target is an important milestone to read unsimplified written texts. The lower target vocabulary in which EFL students cope in the academic scene efficiently is 5000-6000-word families. The receptive vocabulary of students in this study is low and as a result, students may find it difficult to cope with academic work as they continue to higher education.
As stated above the average vocabulary knowledge of the students in the study is 3096-word families. It should be noted that students' vocabulary was measured at the end of grade twelve. Thus, it can be implied that the student"s receptive vocabulary will be lower in preceding grade levels. Meanwhile, the average vocabulary requirement of reading sections is knowledge of 4000-7000-word families. furthermore, the finding from the textbook"s examination showed lower grade textbooks require more receptive vocabulary knowledge than their counterparts.

919
Taking this aspect into consideration it can be stated that the student"s receptive vocabulary will not be enough even to cope with their school textbooks.
The other point here is the gap among students, such wide gap means some students need to increase their vocabulary significantly to reach recommended reading threshold levels and such gap will be difficult for students to account for even with the help of their teachers.
Another fact worth mentioning here is that low receptive vocabulary means even lower productive vocabulary knowledge. It is stated that while the receptive vocabulary develops faster active vocabulary development is slow. In ESL context the development of productive vocabulary requires multiple exposures and considerable opportunities to use (Laufer and Paribakht 1998). Since productive skills are also required to fulfill academic tasks low vocabulary knowledge will affect the overall academic transaction.
Even if textbooks play an important role especially in an EFL context like Ethiopia where textbooks play a central role as language input matching these texts with students' ability is a difficult task. Hansen, (2009) states that the most pressing and important issues in writing school textbooks is controlling the difficulty and appropriateness of textbooks and crafting the books in a way that facilitates readers' move from simple materials to complicated ones. Meeting these goals is a source of problems for writers and textbook designers Richard C. Anderson et al., (1985)states "A vexing problem for textbook writers is matching the difficulty level of the material to the ability level of the child for whom the material is intended" (Anderson et al. 1985). One possible solution to improve the current problem regarding textbooks will be equipping teachers and students with available resource which are targeted to improve student"s vocabulary learning.

Conclusion:-
Textbooks play a central role in the teaching-learning transaction among teachers and students. Due to their role teaching materials must have high standards in all aspects that make it into the textbook. In language classrooms, a well-crafted textbook will benefit students" linguistic development and enables them to meet the learning objectives of their education. For this reason, studying and evaluating textbooks is essential.
The present study evaluated the vocabulary aspect of secondary English for Ethiopia textbooks" reading sections by employing a corpus-based research method. In addition, students, receptive vocabulary was evaluated using Vocabulary Size Test developed by Nation and Beglar( 2007) to indicate if students' vocabulary knowledge matched recommended receptive vocabulary knowledge thresholds.
The result from the study indicated that the textbooks reading sections have, unmatched receptive vocabulary knowledge requirements of reading passages. the vocabulary size test finding showed students in the study did not reach the receptive vocabulary knowledge required for most reading scenarios. Students' average receptive vocabulary in the vocabulary size test showed students' average receptive vocabulary was 3096-word families from the 10000k word families. Also, problem of mastery of the 3000 high-frequency word levels was observed. Even, if the small sample taken for the test will not allow generalization it is sufficient to indicate students' shortage of vocabulary knowledge. Based on the findings it is concluded that the textbooks will be difficult to use as they are. Thus, teachers should employ resources from vocabulary research findings to compensate for the weak attributes of the textbooks.
The limitation of the study is that the results should only be interpreted as being reflective of vocabulary aspects of language textbooks of grades nine to twelve. The receptive vocabulary test findings also should only be interpreted as being reflective of receptive vocabulary knowledge of participants of the study. The results of the current analysis did, however, establish a pattern from which conclusions can be drawn, but more textbooks would need to be analyzed to generalize the pattern to all language textbooks. Further research, which includes an increase in both the number and size of samples of English textbooks and vocabulary tests, are needed to paint the full picture. The results of the current analysis did, however, establish a pattern for evaluating.
The findings from this research is a starting place to inform teachers and students so that they won"t heavily rely on the textbooks. It will not be feasible for teachers to compensate for every problem in the textbooks from limited class time and a limited textbook however being informed of the facts and availing resources like important word lists, text evaluating techniques, and vocabulary tests, will guide students to focus their time and energy on the 920 important items that will assist them in the long term and enable wide use of their vocabulary knowledge to foster their academic journey.

Recommendations:-
Future researches should be conducted to evaluate more textbooks of language and content-area textbooks using similar methodologies. Study types may focus on replication and expansion of evaluation. Also, studies that relate textbook evaluation with students' vocabulary knowledge will be very essential. Studies also must include testing various aspects of students' vocabulary knowledge at different grade levels to assist students" vocabulary learning in particular and language learning in general. Such studies and testing should not be limited to elementary and high school textbooks and students. Rather it will be useful to conduct studied at higher education levels to address the different vocabulary needs across field of studies. Findings from such studies will be useful to tailor and execute study findings to the nature and demand of specific field of study accordingly Policymakers and education stakeholders should carry out researches to evaluate and select appropriate supportive tools and resources that can assist teachers and students and also compensate for textbook language-related deficiencies. Various free technological tools are based on contemporary empirical study findings that can be incorporated with already available resources with lower budget and time requirements. Besides education, stakeholders should work on ways research findings and tools are considered in future material and syllabus designing and textbook improvement projects. Teacher education and related higher institutions should also foster textbook evaluation studies within the framework of language teaching and learning. machine that makes sounds louder c.
machine that makes things look bigger d.
small telephone that can be carried around 10.
PRO: He's a pro. a.
someone who is employed to find out important secrets b.
a stupid person c.
someone who writes for a newspaper d.
someone who is paid for playing sport etc Third 1000: 1.
SOLDIER: He is a soldier. a.
person in a business b. student c.
person who uses metal d.
person in the army 2.
RESTORE: It has been restored. a.
said again b.
given to a different person c.
given a lower price d.
made like new again 3.
JUG: He was holding a jug. a.
A container for pouring liquids b.
an informal discussion c.
A soft cap d.
A weapon that explodes 4. SCRUB: He is scrubbing it. a.
cutting shallow lines into it b.
repairing it c.
rubbing it hard to clean it d.
drawing simple pictures of it 5.
DINOSAUR: The children were pretending to be dinosaurs. a.
robbers who work at sea b.
very small creatures with human form but with wings c.
large creatures with wings that breathe fire d.
animals that lived a long time ago 6. STRAP: He broke the strap. a. promise b.
top cover c.
shallow dish for food d.
strip of material for holding things together 7.
PAVE: It was paved. a.
prevented from going through b. divided c.
given NUN: We saw a nun. a.
long thin creature that lives in the earth b.
terrible accident c.
woman following a strict religious life d.
unexplained bright light in the sky 4.
HAUNT: The house is haunted. a.
full of ornaments b. rented c. empty d.
full of ghosts 5.
COMPOST: We need some compost. a. strong support b.
help to feel better c.
hard stuff made of stones and sand stuck together d.
CUBE: I need one more cube. a.
sharp thing used for joining things b.
solid square block c.
tall cup with no saucer d.
piece of stiff paper folded in half 7.
MINIATURE: It is a miniature. a.
a very small thing of its kind b.
an instrument to look at small objects c.
a very small living creature d.
a small line to join letters in handwriting 8.
PEEL: Shall I peel it? a.
let it sit in water for a long time b.
take the skin off it c. make it white d.
cut it into thin pieces 9.
FRACTURE: They found a fracture. a. break b.
small piece c.
short coat d.
BACTERIUM: They didn't find a single bacterium.
935 a. small living thing causing disease b.
plant with red or orange flowers c.
animal that carries water on its back d.
thing that has been stolen and sold to a shop