A Coh-Metrix Analysis Of Syntactic Difficulty In Textbooks

Textbooks are the major source of language learning.Good textbooks should consider a wide range of critical features,such as practical considerations,four-skill balance,exercises and activities,pedagogical analyses,appropriateness in language and grammar,supplementary materials,etc.However,syntactic difficulty,as one of important components of text difficulty,is my present research interest to assess the progression of a college English textbook series.The study aims to investigate whether and how syntactic features differ across four volumes of college textbooks called New Horizon College English(3~rdd ed.)by means of a computational tool Coh-Metrix.12 syntactic features are grouped into three dimensions:syntactic complexity,syntactic similarity and syntactic pattern density.Data are then collected and compared across four levels by using One-way Analysis of Variance(ANOVA)through SPSS 17.0.It is found that four volumes of textbooks do not constitute a positive increase in syntactic difficulty across grade levels.The difficulty features in syntactic complexity and syntactic similarity have no significant changes as textbooks level up,showing no orderly gradient variation.The only significant differences across textbooks,however,are reflected in the syntactic pattern features,which are realized as noun phrase density,verb phrase density and adverbial phrase density.These significant features varied among four levels,particularly between the beginning and higher level textbooks.Hence,phrasal complexity is the only distinctive index to be found in textbook difficulty among four volumes.Noun phrase density,one of the most distinguishing indices among the three phrase densities,is targeted for a close examination.Based on the hypothesized developmental progression index suggested by Biber,Gray,and Poonpon(2011),the research explores how noun group complexity develops with textbook levels.It is found that different nominal modifications in four textbooks conform to the proposed developmental progression in the sense that the frequency of complex nominal modifications decreases as textbook levels up.For the simple attributive adjectives in the stage 2 and more complex modifications like non-finite relative clauses,preposition+nonfinite complement clause and to-clauses as post modifiers in stage 4 and 5,noun phrase complexity is on the increases as textbook levels up so that textbooks pose a language instruction on language acquisition for students in four grades.However,the gradual lower denser of noun phrases in stage 3 shows the failure in complexity progression across textbook levels.Based on the findings of this study,some suggestions are also put forward in order to achieve a gradient syntactic difficulty in textbooks.For the insignificant variables,textbook compliers should highlight syntactic features in syntactic complexity and syntactic similarity in reading passages and provide other necessary supplemental materials and activities to expose students to these features.Moreover,phrasal complexity is needed to be considered in order to meet the difficulty progression of textbooks.It is suggested that modifications in stage 3,like nouns,prepositions as modifiers need to be compiled reasonably in order to meet the difficulty progression of textbooks.This study will benefit publishers and researchers of the textbooks to judge the difficulty of textbooks more accurately as well as control syntactic difficulty properly.