The research background of Classroom Action Research is based on the low of student’s learning outcomes about extensive flat structure. In which, it’s condition seen from the student’s learning outcomes mostly in under the KKM. For that reason, the classroom action research is implemented in order to improve the learning outcomes of extensive flat structure of mathematic toward grade III Jamus I Sate Elementary School of Magelang regency.
The Classroom Action Research takes place in Jamus I State Elementary School, Ngluwar Sub-district, Magelang regency. The research time is on February 2016 to May 2016 in semester I. The research subjects are grade III Jamus I State Elementary School on Ngluwar Magelang. The research is implemented as the upgrading learning which is implemented in 2 cycles upgrading, and each cycle has 4 stages; planning, action implementation, observation, and refection.
The use of mind mapping in mathematic proves that it is able to improve studen’s of grade II Jamus I State Elementary School of extensive flat structure. It is proved by the completeness achievement in cycle I of first meeting is 74%, in cycle I second meeting become 79%, in cycle II first meeting is 84%, and in cycle III secong meeting is 94%.
Key words: learning outcomes, mind mapping technique.