Solfitri, TitiRahmania, Indah2014-06-262014-06-262014-06-26078-602-19531-0-5wahyu sari yenihttp://repository.unri.ac.id/xmlui/handle/123456789/6414This is an experimental research using Cooperative Learning as a treatment. The objective of the research is identify the effectiveness of the Cooperative Learning on mathematics achievement. Sample of 1st grade student at 8th senior high school in Pekanbaru were used in the studies. The research shows that the Cooperative Learning with Team Assisted Individualization type more effectiveness on mathematics achievement than conventional method. The Cooperative Learning with Team Assisted Individualization type implicate that student active involvement in learning to solve problem will improve their mathematics achievement effectivelyenUR-Proceedings