International educational reformation has recommended the importance of investigation to enhance mathematics learning and develop mathematical power for children (Quinnell, 2010). This research used a qualitative approach involving teacher and student participation in junior high schools (state school and private school owned by an educational foundation) in Indonesia which applied group investigation based learning in mathematics class. The results showed that mathematics learning with investigation approach (group investigation) had succeeded to transform negative disposition into productive (positive) disposition and to enhance productive disposition toward mathematics and had affected the increasing of students’ mathematical power. The students’ mathematical power ability appeared in the reasoning actualization (providing reasons, mathematical communication in groups and connections between ideas in mathematics when they discussed about the investigation result. Result of this study was also in line with Flewelling and Higginson (2003) that investigation, and problem solving suggested an opportunity for students to use their imagination in order to obtain more powerful mathematics ideas and understanding about relationship between mathematical ideas.
Keywords: Investigation, Mathematical disposition, Mathematical power
