Post-test is the final evaluation when the material being taught has been given which is intended to find out whether the student has understood the material that has been taught and learned. The post-test items are same with pre-test items. This test will compare the result scores between post-test of experimental group and post-test of control group in order to determine whether or not there is significant difference in students' scores after the treatment by using Picture Series for the experimental group and conventional  method for the control group.
Questionnaire is a technique of collecting data by asking written questions to be answered in writing by the respondent. "A questionnaire is not just a list of questions or a form to be filled in. It is essentially a measurement tool, an instrument for the collection of particular kinds of data. Like all such instruments, the aims and specifications of a questionnaire stem directly from the overall research design." (Oppenheim,1992:10). Questionnaire is given to students who get the treatments. The questionnaire gives information about the students' responses of the use Picture Series as Teaching Media to improve students' Descriptive Text Writing Skill. The questionnaire consists of 15 questions relating to the topic and research questions.
FINDING and DISCUSSION
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The writer did the research at the First Grade students of Pelita Bunga Bangsa Arjasari Vocational School and took two classes which consisted of 22 students in each class. The research was held for a week from 29th July to 3rd August 2019. At the first meeting the writer gave pre-test to both experimental group and control group. The treatment was given at the second up to the fourth meeting to both experimental group and control group. The experimental was given the treatment by using Picture Series, while the control group was given the treatment by using the conventional method. At the last day the writer gave post-test to both of groups, and gave the questionnaire only to the experimental group.
The pre-test was held on 29th July 2019 both for the experimental and control group. The experimental and control group were given the same pre-test. The form of pre-test was written test which covered completion, re-order paragraph and writing test. From the pretest result of both experimental group and control group, it can be seen from 22 students of experimental group, three students got 23 as the lowest score, one student got 75 as the highest score, and 17 students got score from 27 up to 70 as the middle score. While from 22 students of control group, one student got 34 as the lowest score, three students got 58 as the highest score, and 17 students got score from 35 up to 57 as the middle score.
With the df = N1+N2 = 22+22- 2 = 42, at p = ,05 of two-tailed, the critical value of t is 2.021. As the value of the derived t (to) is lower than that of the critical t (t-table) Â < 2.021, the Null Hypothesis (Ho) is retained. It means that there is no significant difference in the result of the students' understanding on Writing Descriptive Text between experimental group and control group at the beginning of the research. In other words, the experimental group and the control group had similar ability on understanding the writing of descriptive text. Therefore, they are safe to be included into the sample of this research. Thus treatments were given to the experimental group.
The same procedure was used for the post-test. From the post-test result of both experimental group and control group, it can be seen from 22 students of experimental group, three students got 61 as the lowest score, one student got 97 as the highest score, and 17 students got score from 64 up to 94 as the middle score. While from 22 students of control group, one student got 41 as the lowest score, one student got 77 as the highest score, and 20 students got score from 42 up to 74 as the middle score.
With the df = N1+N2 = 22+22- 2 = 42, at p = ,05 of two-tailed, the critical value of t is 2.021. As the value of the derived t (to) is higher than that of the critical t (t-table) Â > 2.021, the Null Hypothesis (Ho) is rejected, and the Alternative Hypothesis (Ha) is accepted. It means that there is significant difference between the use of Picture Series and conventional method in teaching Writing Descriptive text to the first grade students of Pelita Bunga Bangsa Arjasari Vocational School and it also means that Picture Series is effective to be implemented in teaching writing descriptive text to the first grade students of Pelita Bunga Bangsa Arjasari Vocational School.
Meanwhile from 15 questions, the result of questionnaire showed that the first grade of students in Pelita Bunga Bangsa Arjasari Vocational School like being taught writing descriptive text using Picture Series. The result showed that most of the students (91%) like Picture Series to be used in writing descriptive text, almost all of the students (86%) feel helped in writing descriptive text using Picture Series. It means that students gave the positive responses towards Picture Series.
CONCLUSIONS
