ABSTRAKPembelajaran untuk mata kuliah pendidikan matematika yang meliputi teori belajar, perkembangan peserta didik, profesi keguruan, selama dua tahun berturut-turut dilakukan dengan metode ceramah, diskusi kelompok dan penugasan berupa pengerjaan Lembar Kerja Mahasiswa (LKM). Metode ini mengakibatkan mahasiswa jarang melakukan kerja sama untuk mengingat serta memaknai dan mengimplementasikan materi melalui kegiatan microteaching. Inovasi model pembelajaran diperlukan agar mahasiswa mampu berkolaborasi untuk menyelesaikan permasalahan serta mengimplementasikan materi. Tujuan penelitian ini yaitu untuk mendeskripsikan hasil implementasi model pembelajaran REACT dan tinjauannya terhadap kemampuan kolaboratif mahasiswa melalui kegiatan observasi. Implementasi model pembelajaran dilaksanakan sebanyak 8 kali pertemuan dan terdapat peningkatan kemampuan kolaboratif mahasiswa. Kemampuan kolaboratif terlihat dari pengerjaan LKM secara berkelompok dan kerja sama dalam pembuatan desain pembelajaran matematika. Kolaborasi juga dapat terlihat dari kontribusi ide penyelesaian masalah, saran, gagasan, serta pertanyaan yang bersifat konfirmasi. Selain itu, pembuatan serta simulasi desain pembelajaran juga merupakan bentuk kolaborasi anggota tim. Kemampuan kolaboratif terlihat paling jelas ketika tahap Experiencing, Cooperating, dan Transfering. Tahap experiencing menunjukkan mahasiswa mampu menjawab pertanyaan yang didasarkan pada pengalaman pribadi. Tahap cooperating menunjukkan mahasiswa berdiskusi aktif menyelesaikan LKM secara berkelompok. Tahap transferring menunjukkan mahasiswa bekerja sama membuat desain pembelajaran serta mensimulasikan. Dengan demikian, melalui implementasi model pembelajaran REACT, mahasiswa mampu meningkatkan kemampuan kolaboratif.Kata Kunci: model pembelajaran REACT, Relating, Experiencing, Applying, Cooperating, Transferring, kemampuan kolaboratif, desain pembelajaran, simulasi ABSTRACTLearning for courses in mathematics education that includes learning theory, the development of the students, the teaching profession, for two years in a row performed by the method of lectures, group discussions, and assignments in the form of a worksheet. This method makes the students rarely do work together to remember as well as interpret and implement the content through the activities of microteaching. The innovation learning model was necessary so that students could collaborate to solve problems and implement the material. The study aimed to describe the results of the implementation of the model of learning REACT and review on the ability of collaborative students through the activities of observation. The implementation of the learning model implemented as many as 8 meetings and there was an increase in the ability of collaborative students. The ability of the collaborative looks of the worksheet in groups and work together in making the design of learning mathematics. C can also be seen from the contribution of ideas problem solving, suggestions, ideas, and questions that are confirmation. Also, the manufacture and simulation for the design of learning is also a form of collaboration team members. The ability of the collaborative was seen most clearly when the stage of Experiencing, Cooperating, and Transferring. The stage of experiencing showed students are able to answer questions based on personal experience. The stage of cooperating showed students discuss actively resolve the worksheet in groups. The stage of transferring showed students working together to make learning design and simulate. Thus, through the implementation of the learning model of REACT, students could improve the ability of the collaborative.Keywords: REACT Learning Model, Relating, Experiencing, Applying, Cooperating, Transferring, collaborative ability, learning design, simulation