ANALISIS MISKONSEPSI SISWA KELAS VIII PADA MATERI SISTEM PEREDARAN DARAH MANUSIA DI SMP NEGERI SE-KOTA MEDAN TAHUN PEMBELAJARAN 2014/2015

The aim of this research were to improve students` mathematical communication ability and to know how students` activity through guided discovery learning using GeoGebra software on topic of circle equation. The type of this research was Classroom Action Research. The research was conducted to 47 students grade XI at SMA Negeri 13 Medan. Two instruments were used to collect the data: mathematical communication ability test and students` observation sheet. This research was done in two cycles, in which each cycle had two meetings. At the end of each cycle, students were given mathematical communication ability test. The tests were validated by experts as validator before submitted to the students. After treatment in cycle I, the result of 47 students, 11 students (23.40%) gained the score ³ 65 with the average score of class was 51.56. After treatment in cycle II, the result of 47 students, 41 students (87.23%) gained the score ³ 65 with the average score of class 80.07. The observation sheet of students` activity in cycle 1 obtained the total score 81 (81%) classified in good category. The observation sheet of students` activity in cycle 2 obtained the total score 93 (93%) classified in very good category. The result of this research shown that learning by using guided discovery with the help of GeoGebra software can improve students` mathematical communication ability and students` activity.