<p class="Abstrak"><strong>Abstract:</strong> Mathematical spatial reasoning is needed to solve geometric problems. This study aims to describe the mathematical spatial reasoning of perception, namely describing objects when their position changes and visualization, which is describing the material that builds objects. The research subjects consisted of 6 students of class VIII including 2 students with highly capable, 2 students with moderately capable, and 2 students with lowly capable. The results showed that the ability of mathematical spatial perception and visualization in problem solving, namely: highly capable subjects can imagine and draw objects, moderately capable subjects can imagine objects but have not been able to draw objects correctly, and lowly capable subjects still have difficulty in describing objects.</p><strong>Abstrak:</strong> Penalaran spasial matematis diperlukan untuk memecahkan permasalahan geometri. Penelitian ini bertujuan untuk mendeskripsikan penalaran spasial matematis persepsi yaitu menggambarkan objek ketika posisinya berubah dan visualisasi yaitu menggambarkan materi yang membangun objek. Subjek penelitian terdiri dari enam siswa siswa kelas VIII, yaitu dua siswa berkemampuan tinggi, dua siswa berkemampuan sedang, dan dua siswa berkemampuan rendah. Hasil penelitian menunjukkan bahwa kemampuan persepsi dan visualisasi spasial matematis pada soal pemecahan masalah,  yaitu subjek berkemampuan tinggi dapat membayangkan dan menggambar objek, subjek berkemampuan sedang dapat membayangkan objek namun belum dapat menggambar objek secara tepat, dan subjek berkemampuan rendah masih kesulitan dalam menggambarkan objek.

Communication is an important aspect in learning mathematics. In the process of learning mathematical communication, there is a standard communication process that must be met. The purpose of this study was to describe mathematical communication ability on direct proportion topic and inverse proportion topic using a scientific approach and to explain the factors inhibiting mathematical communication ability. The design of this research was qualitative descriptive research. The instruments used were lesson plans, modules, worksheets, and documentation. The research results that were obtained included achievement of mathematical communication process standards such as (1) organizing and consolidating students' mathematical thinking through communication, (2) communicating students' mathematical thinking coherently (logically) and clearly to friends, teachers, and others, (3) analyzing and evaluating mathematical thinking and strategies used by others, and (4) using mathematical language to show mathematical ideas appropriately in each peer teaching activity.

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