3.2.1 Source of the Materials
In selecting the irregular verbs, the researcher used several kinds of exercise books and test sets as the sources to collect the verbs. They were five sets of tests and five sets of
exercise books which had been reviewed by the teacher. The tests were “Ulangan Harian Terprogram III” year of 2014, “Mid Semester Test” year of 2014, “Ulangan Akhir
Semester Gasal” SMPMTs Kota Semarang in the academic year of 20122013, “Penjajakan Ujian Nasional” in the academic year of 20112013 Tahap III Conducted by
Educat ional Office Semarang, and “Ujian Sekolah” in the academic year of 20112012.
The five sets of exercises books were “Soal Prediksi Ujian Nasional 20102011 I” from Sukses Membidik Ujian Nasional Bahasa Inggris untuk SMPMTs, “Prediksi UN 1” and
“Prediksi UN 2” from SPM Bahasa Inggris SMP dan MTs, “Review 3” from TOPS: Siap UN Bahasa Inggris SMP, “Paket Soal 1” from TOPS: Siap UN Bahasa Inggris
SMP, and “Prediksi 1” from English Prediction Worksheet. The researcher listed all the irregular verbs which appeared in the sources and noted the frequencies of their
appearance.
3.2.2 Reduction of the Inventories’ verbs
After collecting the irregular verbs from the sources, the researcher found ninety verbs. The verbs were listed from the verbs with high frequencies of appearance to the verbs
with low frequencies of appearance. The list of the verbs is available in Appendix 2. Because of the limited time of this study, the researcher only used some of them. There
were only thirty verbs that would be used in this study. Therefore, she reduced some verbs. The selection of the verbs was explained in the next subchapter.
3.2.3 Selection of the verbs
As explained before, only thirty verbs were used. Therefore, the researcher selected them. The selection was based on the frequency of appearance. She only used the first
thirty verbs which had the highest frequency of appearance. The range of the frequency of appearance that was selected was from 13 to 400 times. The researcher dropped the
verbs which had frequency of appearance from 1 to 12 times. The list of the verbs is available in Appendix 3.
3.2.4 Selected verbs
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