Abstract
This study examines the relationships between sentence-structure awareness and reading comprehension. The significance of this study lies in the possibility that knowledge of text structure may create connections among the disciplines which could enhance understanding of content and promote thinking and reading comprehension abilities. After administering a standardized reading comprehension test, a group of 64 high school students was selected from a total population of 84. The selected subjects were randomly assigned to experimental and control groups. For the experimental group, the researcher administered a treatment which lasted for 4 weeks, two 90 minute sessions per week. During the experiment, both groups had the same instructor, curriculum, and schedule of instruction, while in the control group, the students had conventional learning methods, as they worked just with the reading passages without any explicit instruction or without any awareness, by being underlined, about the types of structures which were the target structure of the researcher, namely, adjective clauses, gerunds, and infinitives. For the experimental group, they received explicit instruction and awareness about the types of structures which were the target structures of the researcher. At the end of the study, the obtained scores on the pre- and post-tests were analyzed through different statistical procedures. The results showed that being aware about sentence structures and the explicit teaching of grammatical structures had a significant effect on improving Iranian high school students’ reading comprehension performance. The results also indicated that significant relationships exist among the variables of sentence-structure recognition and reading comprehension. These associations support the theory that students may use sentence structure to improve thinking and reading comprehension processes. This association provides educators with a potentially powerful way to structure instruction. 1. Introduction

Reading for full comprehension and learning is a special type of reading, which needs a different type of processing in terms of focusing attention, and information encoding and retrieval from reading for enjoyment, or reading for general information. Sentence-structure knowledge (awareness) helps a reader to see relations between ideas, including relationships between main ideas and details and also relations among each part of the components of a sentence in order to have a better analysis of the text and sentences, and hence a better understanding of them. According to Mandler & Johnson, in both L1 and ESL, students who have been taught how to identify text structure and use this knowledge to guide their reading process have showed better comprehension and recall of information than readers lacking such knowledge (Mandler & Johnson, 1977). Students who are reading texts need to work actively at finding and using appropriate cues in texts in order to enhance their understanding. Research has indicated that understanding how a passage is structured is an important factor in reading comprehension (Mandler & Johnson, 1977; Meyer,