The background of this research is based on the phenomenon that learning pronunciation is seen as one of the language item that is difficult to be learnt. Then, diphthongs was chosen because it is the most common mistakes that are done by the people especially students. They often produced pure vowel where diphthongs should be pronounced. This research is aimed to find the answer to the following research question: How effective is the use of TBL (task-based learning) in teaching diphthongs to the 2nd semester students of intermediate speaking class of ELT Department of Education and Teacher Training Faculty of IAIN Walisongo in the academic year of 2012/ 2013? The study was to find out whether or not TBL (task-based learning) is more effective to improve the students’ pronunciation on diphthongs.
This study employed the experimental design. The 2nd semester students of intermediate speaking class of ELT Department of Education and Teacher Training Faculty of IAIN Walisongo in the academic year of 2012/ 2013 was selected as the research source of data. The classes were divided into experimental group and control group. Class TBI 2A is as experimental group and Class TBI 2B is as control group. The methods of data elicitation used here were documentation and test. The data were obtained by employing the relevant pre test and post test.
Hypothesis showed that the use of TBL (task-based learning) method was effective for teaching diphthongs. It could be seen from the result of the test score, it showed that experimental class which was given treatment by using TBL (task-based learning) method got higher score that was 73.12, compared to the control class who were not given the same treatment. The control class got 66.76. The use of TBL (task-based learning) method was more effective than traditional method. It is caused tcount (2.167) is higher than the ttable (1.67). Finally the researcher suggests that for the English teacher, they have to be creative in teaching diphthongs or other materials, for example by using TBL (task-based learning) method, so that the students will understand the material better. For the students, the use of TBL (task-based learning) method will help them to understand the material easily, so that they can improve their ability in mastering English.
The main finding of the study was the experimental and control group were equivalent at the beginning of the experiment and the teaching and learning of diphthongs through TBL (task-based learning) method played positive role in improving the students’ academic understanding.