This study aims to describe the adaptive reasoning of students in solving beam mathematical problems with high, medium, and low mathematical solving abilities. The research location is at Siti Aminah Surabaya elementary school, with 24 students in grades VI-A and will take 3 students as research subjects. This study uses qualitative research, by conducting several stages, namely, preparation, implementation, and analysis. Data analysis techniques used observation methods, tests of ability to solve mathematical problems (TPMM), and interviews. The results showed students with high mathematical abilities students were able to collect data then identify the components of the building blocks, be able to provide evidence and explanations and verify what he had obtained. Students with mathematical abilities while students are able to understand the problem by reading repeatedly to be able to explain and verify their findings. Students with low mathematical abilities are able to understand after doing trial and error, understanding from many data sources. From the experience and data sources obtained by students, they are only able to understand the problems, construct and connect with objects around them, gather information, so they can provide an explanation of the concept and verify it.