Tujuan penelitian ini adalah menghasilkan bahan ajar berbasis discovery learning melalui pendekatan etnomatematika pada materi transformasi geometri yang layak (valid, praktis, dan efektif) dan sesuai kebutuhan peserta didik. Jenis penelitian ini adalah Penelitian dan Pengembangan (R&D) dengan menggunakan model Plomp yang terdiri dari lima tahap yaitu prelimenary investigation; realization/construction; test, evaluation and revision; dan implementation. Instrumen yang digunakan yaitu berupa lembar angket validasi, lembar respon peserta didik, lembar observasi keterlaksanaan bahan ajar, dan soal tes hasil belajar. Berdasarkan penelitian diperoleh hasil validasi ahli dengan persentase 83% (sangat valid), responden peserta didik 84,50% (sangat praktis), dan keefektifan 85,71% (tinggi). Berdasarkan penelitian pengembangan ini kelebihan bahan ajar tersebut yaitu materi bahan ajar berkaitan dengan etnomatematika pola Batik Lampung pada penerapan konsep transformasi geometri. Kelemahan bahan ajar yang dikembangkan yaitu pembahasan materi terbatas pada jenis transformasi geometri dan uji efektifnya hanya berdasarkan KKM. Pengembangan produk selanjutnya, materi bahan ajar dapat mencakup keseluruhan materi transformasi geometri dengan kajian etnomatematika budaya Lampung lainnya dan uji efektifitas diuji secara menyeluruh dari mulai hasil belajar, aktivitas dan kemampuan peserta didik.

The purpose of this study to describe the error and to know the cause of student error in solving trigonometric problems based on Newman's Theory and cognitive style. The type of this research is qualitative descriptive research conducted at SMAN 1 Sekampung Udik. Selection of research subjects using purposive sampling selected 4 research subjects with 2 subjects have a cognitive style reflective and 2 subjects have impulsive cognitive style. Data collection techniques used were tests and interviews, while the instruments used were: (1) cognitive style test or MFFT (Matching Familiar Figure Test), (2) trigonometric problem test, and (3) interview guides. The results of this study can be described as follows. ( 1) students who have a reflective cognitive style in solving trigonometric problems tend to make mistakes in the stage of transformation error and process skill error; and encoding error, (2) whereas students who have an impulsive cognitive style in solving trigonometric problems tend to make mistakes in the phase of comprehension error, transformation error, process skill error, and encoding error. (3) The cause of the errors of cognitive and relative impulsive cognitive students are the students can not understand the problem well, forget the formula, less thorough in solving problems, rush in solving problems, not used to write conclusions, and run out of time in solving problems

The purpose of this research is to improve students mathematics learning outcome through Problem Based Learning (PBL) with QR-Code on MIPA class grade X SMA Negeri 1 Kotagajah (Senior High School in Kotagajah). This research is an Action Research Class. The subject of this research is 36 Students. This research is cyclus research with Kemmis and Mc Taggart Models consisting of: (1) planning; (2) implementation; (3 observation; and (4) reflection. Data collection technique is using in this research is tes. Based on the research result, then obtained the conclusion is Problem Based Learning with QR-code can improve students mathematics learning outcome on MIPA Class grade X SMA Negeri 1 Kotagajah. This matter showed a percentage value on the first cyclus is 47,22% and increase on the second cyclus to be 63,89%.

Teaching materials is one important component in learning because teaching materials can be used for independent study. On the other hand, the lack of teaching materials are on open-ended problems leads to an underdevelopment of creativity in learning. With the open-ended problems, students are expected to have more than one solution to solve problems in everyday life, especially in mathematical problem solving. The purpose of this study is to develop teaching materials based on open-ended valildly, practically and effectively in the subject of linear algebra. This research is the development by using Plomp models which consists of three stages: preliminary research, prototyping, and assessment. Data collection technique through observation, questionnaires and tests. The instruments used were observation sheet, questionnaire sheet and a test sheet. Based on result of the research that has been done shows that the teaching materials is based on open-ended in the subject linear algebra that have been developed otherwise valid with a value of 3.43, practice with a value 3,11 or in the percentage reached 77,75%, and effective with value of learning outcomes experiment class (use teaching materials developed) higher than control class.

The aims of the research is to describe the thinking process at mild intellectual disability students to solve mathematics problem. The research was a descriptive qualitative. The subjects of the research was students of grade eight SMPN 5 Metro. Technique analyzing of the data were: (1) classifying the data, (2) presenting the data, and (3) concluding the data in each categories. The results of the research showed that thinking process for mild intellectual disability students : (1) mild intellectual disability students can establishnment understanding in thinking process; (2) mild intellectual disability students can’t establishnment opinion and students cant’t using the right strategy to solve mathematics problem; (3) mild intellectual disability can’t give conclusion.Keywords: mathematics problem, mild intellectual disability, thinking process