This study is to understand how high school English textbook modification affects its readability and cohesion. Even though there are ongoing debates on which type of material, authentic or modified, is more advantageous to learning English.
Reading passages in English textbooks, in most cases, are modified from their original sources(authentic materials). In EFL(English as a Foreign Language) settings, text modification is beneficial mainly due to low English proficiency level of students. Authentic materials are modified in such a way that their contents, construction, and the level of difficulty, etc. are adjusted according to the students’ proficiency level so that the modification assists students to learn authentic material more easily.
Thus text modification is necessary in writing English textbooks. Analyzing in detail how text modification is carried out, through the comparison between the authentic and the modified materials, would be beneficial to writing English textbooks and eventually to English education.
In this respect, the linguistic features including text difficulties of the reading passages of high school English textbooks and those of their original versions are compared through a program called Coh-Metrix, an automated web-based tool for linguistic analysis in this research. Among 108 indices that the program analyzes, 15 indices analyzing text readability and cohesion are selected, and 9 reading passages are compared to their original versions in this study.
The results show that six out of nine modified passages are easier, and three are more difficult than the originals. However, two out of those three passages shows insignificant changes with regard to the text difficulty.
Such results suggest that the most of the reading passages of English textbooks become easier to read after modification. Additionally, one of the 15 indices that influences readability the most through text modification was found to be the average sentence length. Eight out of nine passages showed different readabilities in terms of average sentence length. That is, passages which were more difficult tended to contain longer sentences compared to their originals and vice versa.
This study also revealed that the referential cohesion of most of the passages increased through text modification. Considering that the most of the passages became easier, the referential cohesion is regarded to be an important factor influencing the text readability among the 15 indices. That is, when increasing the text readability, cohesion should also be considered in the process of text modification.
In conclusion, this study shows that text modification brings various changes in text readability and cohesion of reading passages in high school English textbook. Through this research, it is found in general that the modification improves readability. Among 15 indices, reducing the average sentence length; using same nouns, arguments, and stems in adjacent sentences were the most influential factors for increasing text readability. This also implies that cohesion is closely related to readability.