The impact of Gass's second language acquisition model for developing vocabulary in Turkish teaching as a second language

Acquisition, enrichment and teaching of vocabulary in Turkish teaching as a second language is very important. There are many methods and techniques used to enrich vocabulary. It is thought that studies should be done to improve the vocabulary in acquisition of the second language. This study will introduce Gass's Second Language Acquisition Model which believed to bring a new perspective to foreign language teaching. In our work, hierarchical vocabulary activities were organized on the basis of Gass's Second Language Acquisition Model. It is the most important point of the research that these activities have a certain hierarchy according to their level of learning (awareness input, understood input, internalization, integration and output). In this context, the primary purpose of this study determine that learner will learn better the new words in the texts by making the hierarchical vocabulary activities or the activities taking place in the book. For this purpose, a mixed method research is carried out which includes dependent and independent variables which show causal relation. The research was conducted with a total of twenty-eight students who were educated at İnönü University TÖMER at B2 level during 2015-2016 academic year spring semester. Experimental and control groups were instructed on 133 target words /phrases and Vocabulary Scale was used as a pre-test, post-test and permanence test. The qualitative part of the research constitutes the opinions of the students through the semi-structured interview form. The Mann Whitney-U test was used to measure the success of the experimental and control groups, while the Wilcoxon test was used when the changes in the groups were investigated. In addition, the responses of the groups to each word or phrase were measured by the chi-square test. According to the results of the study, the pre-test scores (x̄ = 18,857) of the test group were found to be lower than the pre-test scores (x̄ = 29,500) of the control group. According to these findings, it was determined that the students in the experimental group started at the lower level of the control group to in term of target words in the pretest. The difference between the groups' mean total post test scores for the target vocabulary was significantly found to be in favor of the experiment group (Mann Whitney U = 18,500; p = 0,000 <0,05). In addition, the means of the total permanence test scores for the target vocabulary were significantly higher in the experimental group than in the control group. In addition, the difference between the mean of total retention test scores for the target verbal entity was found to be significant for the experimental group (Mann Whitney U = 34,000; p = 0.003 <0.05). It is possible to say that the teaching of the experiment group students has an important success in permanence. Finally, it can be said that Gass's second language acquisition model contributes greatly to the field writing, and it will give a light to other works to be done. Key words: Gass, Second Language Acquisition, Vocabulary Scale, Hierarchical Vocabulary Activities.