The effectiveness of extensive reading towards students' vocabulary mastery: a quasi-experimental study at the seventh grade students of SMP Darussalam Pondok Labu Jakarta.

This research was carried out the effectiveness of extensive reading towards students? vocabulary mastery in the seventh year students of SMP Darussalam Pondok Labu, Jakarta academic year 2013/2014. The method used in this research was quasi-experimental study. It consist two classes of research: experiment class and controlled class. The research was begun by giving pre-test question in each class, treatment manipulation in an experimental class and a post-test to know is there any increasing score before and after treatment in the end of meeting. The population of this research is seventh grade students and the sample of this research are VII-3 as the experimental classes, while VII-2 as the controlled class. There were 29 students in each class. The researcher used purposive sampling to get the samples. To see the differences result among the two classes, the researcher used t-test to analyze the data. The result of this research showed that there was effectiveness of extensive reading towards students? vocabulary mastery. It can be seen from data gotten after the holding of pre-test and post-test. Based on the data, the score which is gained by the experimental class students (512) is more than score gained by the controlled class students (214). According to statistical calculation with the degree of significant 5% showed that the to value in experiment class is higher that t-table value, namely 4.69 > 2.00. Therefore, it proves that (Ha), which states that extensive reading is effective towards students? vocabulary mastery