participated as the sample of this study which were taken from class VI A and B. They were determined as the sample of this study by using purposive sampling
technique since class VI C had taken part in the instrument try-out.
D. Research Instrument
The kinds of instruments used were tests encompassing: 1. Critical Thinking Test
The number of the critical thinking test items comprises 37 questions in the form of multiple choices having two to five alternatives. The scheme and test
specification of this test follows and are similar to the Watson-Glaser Critical Thinking Appraisal®
. There are five sections included in this test consisting of inferences, assumptions, deductions, interpreting information, and
arguments see the instrument specification in Appendix 1. The tryout of critical thinking test was conducted to some students who had the same level
as the targeted participants of this study. Based on the instrument try-out result, it shows that the score of this test validity is various shown by the
discrimination index DI from 0.11 to 0.67. From the 37 items, there are 17 items included as the good or valid ones since these pass the threshold score
of validity DI 0.30, whereas the remaining test items of which DI= 0.11−0.29 were revised before these were administered to the targeted
participants see Appendix 5. Besides, the reliability of this test, measured by using Kuder-Richardson KR-20 equation, indicates a fairly high reliability
that is shown by the reliability score 0.60 see Appendix 6; 2. Test of Written English Independent Essay
This test is provided to find out the students’ writing ability. There are four
topics to develop by the participants in this test. The topics are taken from TOEFL®. Additionally, the analytic scoring is used to
assess the students’ writing ability.
E. Technique of Data Collection
Before the data were collected, the researcher firstly made sure that he got the consent and agreement to conduct this study to Department of English
Education as well as the consent to the participants about the time on which they could take part in this study. The test battery of this study is chronologically
portrayed as follows: 1. Test Battery of Critical Thinking Test
a. First, the participants’ identities which comprises student’s name,
student’s register number NIMNomor Induk Mahasiswa, and student’s signature were taken. They were asked to fill the attendance list that
covered those participants’ personal identities; b. Next, as the participants had already completed writing their identities on
the attendance list, they were informed about the instructions related to the critical thinking test, and then when they were ready to do the test, the
researcher started to time and watch the test taking place; c. The participants were asked to answer all the questions consisting of 37
items related to critical thinking on the answer sheet provided around 30 minutes;
d. After the participants completed this test, their answer sheets were rated and their result were analyzed;
2. Test Battery of Test of Written English Independent Essay a. The test of written English was administered exactly after the participants
had already finished doing the critical thinking test. It was conducted simultaneously in the same day and occasion as critical thinking test;
b. Next, the participants were informed both about the instruction to do this test and about the scoring criteria of their writing response;
c. The participants were freely to choose only one of the four topics given; d. The participants were asked to do this test around 30 minutes with a
condition that their writing should be approximately 300-350 words length;