Validity Reliability Validity and Reliability of Instruments

which it did not satisfy the accounting teacher, the researcher and the school yet. The percentage of students who completed a test in debtors account management topic was 58.82, while the school expected the students to reach more than 75. From the analysis of the pre-test, proceesing actions were held to create understanding, learning achievement, and learning activities, especially for debtors account management topic. b. Action Stage Actions were planned carefully which later would be consulted with the accounting teacher as a reference to implement the actions. The researcher composed observation sheets that would be used to assess students’ affective and psychomotor learning achievement during teaching and learning processes. Observation sheets also functioned to assess the teacher’s performance in teaching using Problem-Based Learning model. Meanwhile, for evaluation tools, the teacher and the researcher created a test consisting of multiple choice questions and essays to find out the level of students’ understanding toward reserve for possible losses topic. In this stage, the teacher implemented PBL model based on the lesson plans. During the teaching and learning processes, the teacher attempted to explain reserve for possible losses topic using PBL model that were carried out in three meetings. 1 Meeting 1 In meeting 1, the topic was managing provision for doubtful debt with indicators: a explaining receivable determination, b explaining bookkeeping of reserve accounts, and c explaining procedures of recording provision for doubtful debt. The teacher started the lesson by greeting, saying prayer and checking students’ attendance. She then gave apperception about the topic being discussed. In the core activity, the teacher explained the topic before starting a new topic. She invited students to discuss reserve for possible losses with their groups. Yet, before that, the teacher grouped the students. The students than discussed questions that the teacher gave. After discussing the answers to the questions, a representative of each group presented the answer in front of the class, while the rest gave comments on it. In the final activity, the teacher evaluated the topic that was presented by some groups. The other groups who had not presented yet would present their answers in the next meeting. 2 Meeting 2 In meeting 2, material for managing debtors account was provision for doubtful debt with indicators: a explaining receivable determination, b explaining bookkeeping of reserve accounts, and c explaining procedures of recording provision