[Bahasa]: Keterampilan abad 21 terdiri dari keterampilan communication, collaboration, critical thinking and problem solving, serta creative and inovative. Keterampilan ini perlu di implementasikan guru dalam proses pembelajaran agar kualitas pembelajaran meningkat. Terbatasnya pengetahuan guru terhadap keterampilan pembelajaran abad 21 menjadi kendala pelaksanaan di dalam kelas. Oleh karena itu, perlu upaya pengenalan keterampilan pembelajaran abad 21 ini kepada guru agar dapat diimplementasikan dengan baik di kelas. Kegiatan pengabdian masyarakat ini dilaksanakan di MTs Massaratul Muta’allimin Banten dengan jumlah peserta sebanyak 8 guru. Kegiatan ini bertujuan untuk mengoptimalkan pemahaman guru terhadap keterampilan pembelajaran abad 21 dan cara mengimplementasi-kannya dalam proses pembelajaran. Pengabdian ini dilakukan dengan cara sosialisasi melalui penyampaian materi kemudian dilakukan evaluasi di akhir kegiatan yang terdiri dari tiga tahapan yaitu tahap awal, inti, dan akhir. Berdasarkan hasil angket di akhir kegiatan diperoleh data bahwa 78,13% guru memahami cara penyampaian materi, 78,13% guru dapat memahami materi dengan baik, 82,29% guru memberikan respon terhadap manfaat kegiatan, dan 81,25% guru dapat mengembangkan proses pembelajaran abad 21 di kelas. Dapat disimpulkan bahwa kegiatan pengabdian ini dapat mengoptimalkan pemahaman guru di MTs Massaratul Muta’llimin Banten terhadap keterampilan pembelajaran abad 21. Kata Kunci: keterampilan abad 21, communication, collaboration, critical thinking and problem solving, creative and inovative [English]: The 21st Century skills consist of communication, collaboration, critical thinking, and problem-solving skills, as well as creative and innovative. This skill needs to be implemented by the teachers in the learning process so that the quality of learning increases. The limitation of teachers’ knowledge of 21st-century learning skills is an obstacle for implementation in the classroom. Therefore, it is necessary to introduce this 21st-century learning skill to the teachers so that it can be implemented well in the classroom. This community service program was carried out at MTs Massaratul Muta'allimin Banten with eight teachers as the participants. It aims to optimize teachers' understanding of 21st-century learning skills and how to implement them in the learning process. This program was held by means of socialization through the delivery of material then an evaluation was administered at the end of the activity in three stages namely the initial, core, and final stages. The results of the questionnaire at the end of the activity show that 78.13% of teachers understand how to deliver the material, 78.13% of teachers can understand the material well, 82.29% of teachers respond to the benefits of the activity, and 81.25% of teachers can develop 21st-century based learning process in the classroom. It can be concluded that this program can optimize teachers’ understanding of 21st-century learning skills. Keywords: 21st century skills; communication, collaboration, critical thinking and problem solving, creative and innovative

Multimedia interaktif berbasis android merupakan salah satu sistem operasi yang mendukung program   pembelajaran, memiliki karakteristik dalam mendorong mahasiswa untuk dapat melakukan belajar secara mandiri tanpa harus dibimbing. Multimedia interaktif berbasis android perlu dikembangkan di setiap jenjang pendidikan merupakan inovasi dalam penyajian materi pembelajaran. Tujuan penelitian adalah mengembangakan multimedia interaktif berbasis android yang valid pada materi kualitas instrumen evaluasi. Metode penelitian yang digunakan merupakan penelitian dan pengembangan (research & development) dengan model pengembangan 4D Thiagarajan terdiri dari pendefenisian (define), perancangan (design), pengembangan (develop), dan penyebaran (disseminate). Hasil pengembangan multimedia interaktif berbasis android memperoleh respon positif dari ahli materi, media serta bahasa dengan kategori kevalidan tinggi dan sudah layak digunakan.Development of Android-based interactive multimedia on the quality of mathematics learning evaluation instruments AndroidAndroid-based interactive multimedia is an operating system that supports learning programs, has characteristics in encouraging students to be able to study independently without having to be guided. Android-based interactive multimedia needs to be developed at every level of education as an innovation in the presentation of learning materials. This research aims to develop a valid Android-based interactive multimedia on the quality material of the evaluation instrument. The research method used is research and development with the Thiagarajan 4D development model consisting of definition, design, development, and dissemination. The results of the development of interactive multimedia based on Android received a positive response from the material, media, and language experts with categories suitable for use.

This article discussed about theory applaying learning according Van Hiele is learning that focus on Geometry. This theory is found that to study Geometry the student have a development to think step by step certain. The steps student cognitive level consist of 1) Visualisation level is introducing level, 2) Analisys level is description level, 3) Abstraction level (deduction informal) is arraged level or relational level, 4) Deduction formal level, and 5) Rigor level is systhematys level.  This implementation in the class Van Hiele determine some of learing faces 1) Information is about question answer  for introducing the student, 2) Direction method is about the students to know the topic that have been learned by tools with accorate that have prepared the teacher make some observation, 3) Explication is explain a view appear about structure that have observation, 4) Free orientation is how the students faced task more than a way and task  open ended and fase and 5) Integration is the students observe review and resume that have learn. Study applying theory Van Hiele more than applying on student activity, because student activity is role important on the procees of learning used study applying theory.

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Abstract. The purpouse of this study is to know the understanding of the mathematical concepts of students with the application of REACT learning strategies better than the understanding of mathematical concepts of convensional learning students. This type of research is Quasi Exsperiment with Randomized Subjects Posttest Only Control Group Design. Population of students of class VIII SMP Negeri 3 Pasir Penyu. Sampling is done by Random Sampling. The classes selected to be the experimental class are class VIII4 and the control class is class VIII3. Data collection techniques used test instrument understanding students’ math concepts. The technique of data analysis using t-test as hypothesis test, with pre- requirement test is normality test and homogeneity test. Based on the calculation of the dip- t test taritmethic =2,113 and 𝑡𝑡𝑎𝑏𝑒𝑙 =2,005, because 𝑡𝑎𝑟𝑖𝑡𝑚𝑒𝑡ℎ𝑖𝑐>𝑡𝑡𝑎𝑏𝑒𝑙 so it can be concluded that 𝐻𝑎 accepted means the hypothesis proposed in accepted researcth that is the understanding of mathematical concepts by applying REACT’s strategy of learning is better than the understanding of mathematical concepts of students using convensional learning class VIII SMP Negeri 3 Pasir Penyu.Keywords: Relating, Exsperiencing, Applying, Cooperating and Transfering (REACT), understanding concepts.