Analysis of mathematical communication instruments on the material of flat side space

This study aims to describe the results of the analysis of the mathematical communication ability test instrument for junior high school students on the material of flat-sided geometry. The questions are made based on indicators of mathematical communication skills, namely drawing, mathematical expressions, and writing. Instrument validation is carried out by expert judgments consisting of lecturers and teachers. The instrument was given to students who have studied flat-sided geometry to calculate the validity, reliability, discriminating power and the level of difficulty. The results of the instrument test show that the mathematical communication ability instrument is appropriate and feasible to be used in the flat-sided geometry for junior high school students.