C. Population and Sample of the Study
The population of this study was eleventh grade students of SMA Kharisma Bangsa, academic year 20152016, included 80 students from 4
Classes. From the population, 35 students were chosen as the participants of this study. 35 students who has been selected as the sample of the study was
determined by using purposive sampling technique. Purposive sampling technique means taking sample based on the certain purpose. Two classes were determined
as the participants of this study based on the average ability both have. In this case, 35 students from eleventh graders B and eleventh graders D class were
selected and being the subjects of this study.
D. Research Instruments
In this study, there were two instruments to collect the data which were administered to the participants students of SMA Kharisma Bangsa. The
instruments were critical thinking test which attempt to measure students critical thinking skill, and reading test which is used to measure students reading
comprehension skill. Those instruments were used in order to achieve the goal of the study; to find out the correlation between those variables. Here, is the specific
information of the research instruments:
1. Critical Thinking Test
Cornell Critical Thinking Test was used to test students critical thinking skill in this research. The CCTT is a standardized test developed by R. Ennis,
Millman, and Tomko in 1980
2
. In this study, level X was chosen as the instrument to measure the students’ critical thinking skill as the samples of
this study were twelfth grade students. This test was considered suitable to be used in the present study because it is claimed by its developers to be a
general critical thinking test which attempts to measure the critical thinking skills as a whole and it is best used for grade 9 to 12. Moreover, the test has
been widely used throughout the world more than twenty years to measure critical thinking skill. Additionally, level X was chosen by several researchers
2
R. Ennis, Millman, and Tomko in 1980. Vocabulary learning and instruction. Review of Research in Education, 13, 91-128.
Isik H. to measure students critical thinking skills. see the instrument in Appendix 1.
The CCTT was already being tested in the term of validity and reliability. The developers argue for the construct validity of the CCTT based on its
content validity. The test was developed based on a sound rationale and that the test items were intensively discussed by the test developers who were
scholars involved in the Illinois Critical Thinking Project. Meanwhile, the developers claimed that the reliability coefficient of the CCTT Level X ranges
from .67 to .90.
2. Reading Test
Reading Test used in this test is reading comprehension practice test of SAT test. The reading test type is descriptive text. The test consists of 50
questions including three types of questions. Each types of question will be given a practice example questions. The students is given 30 minutes to do the
test as much as they can. See the Reading Comprehension Test in the Appendix 2. In addition, the reading test used in this research has already to
be tested in the term of validity and the reliability of each question.
E. Technique of Data Collection
Before collecting the data, the researcher rechecked to make sure that the students were ready to do the test. The first test that was being administered was
critical thinking test and continued by reading test.
a. The Steps of Critical Thinking Test
1 Firstly, the participants were asked to fill out the name, date of
birth, grade and students’ number in the answer sheet. 2
The participants were asked to read the direction of the test 3
The researcher explained the direction of the test and how to answer the test. After the participants were ready, the test was started and
the researcher supervised the test took place.
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