C.
The Population and Sample of the Study
The population of this study was the entire tenth grade students of SMAN 5 Tangerang Selatan. The tenth grade students at this school were 262 students
which were divided into seven classes i.e. X-1 consisting of 37 students, X-2 consisting of 36 students, X-3 consisting of 38 students, X-4 consisting of 38
students, X-5 consisting of 38 students, X-6 consisting of 37 students and X-7 consisting of 38 students. Thus, the population of this study was 262 students of
the seven classes In taking samples for this study, the sampling technique that was used was
purposive sample or what was called as a judgment sample. It was a sampling technique in which the researcher selected the study sample using her experience
and knowledge of the group to be sampled.
2
In other word, the researcher was allowed to use her consideration or judgment in selecting sample that was
believed to be representative of a given population. And, since the researcher only used her belief and consideration to select the samples; this sampling technique
did not guarantee that the selected samples were trully representative as random sampling did. In this case, the study samples that were considered to be
representative were class X-3 and X-4. It was because, as suggested by the English teacher at the school, the two classes had English quality which was not
too far different. It wa s proved by the result of students‘ average pretest scores
from the two classes. Class X-3 got average score around 40.86, while class X- got average score around 48.03. Class X-3 was then used as sample for the
experimental group and class X-4 was used as a sample for the control group.
D. The Instrument of the Study
The instruments that were used in this study were test and interview. Test was used as a main instrument for this study, while the use of interview was as a
secondary instrument for this study.
2
L. R. Gay, et.al, Educational Research, New Jersey: Pearson Education, 2009, p. 135-136
As a main instrument for this study, test was used to collect data about students‘ score in each group before and after treatment. Such data was needed to
find out which group that had significant higher mean score; either it was an experimental group or a control group. This information was obviously needed to
determine whether the use of CALL in teaching past tense was effective for students or not. However, before the test was delivered to the sample, such test
had to be tested in term of its validity and reliability. The next was interview. Interview was also used in this study as a secondary
instrument. It was used to collect data about students‘ opinion equipped with their
reasons for answering two questions which were directed to bear a conclusion i.e. whether CALL was effective in teaching past tense or not. The interview was held
to 12 students in the experimental class. They were selected by using purposive sampling technique i.e. by considering their pretest scores. In this case, the use of
pretest score was as a guide to find which student who had highest, middle, and lowest pretest scores and to analyze whether there was significant increasing mean
score from their initial scores to final scores. From each pretest score level, only four students were taken as interviewees. The interviewees were then showed
their pretest and posttest scores and then asked the following questions:
Figure 3.2 Interview Questions
Questions for the interviewees who get high gained score:
Questions for the interviewees who get low gained score:
―Look Your past tense score increases so high. So, do you feel
motivated to learn past tense using CALL? Why? And, do you feel easy
to understand past tense using CALL? Why?
―Look Your past tense score increases just a little. So, don‘t you feel
motivated to learn past tense using CALL? Why? And, don‘t you feel easy
to understand past tense using CALL? Why?
The answers for such questions were useful to make a conclusion and suggestions for this study.
