The purpose of this study is to investigate students’ mathematical understanding of patterns. Three
7th grade students who were enrolled in a public school solved the questions regarding the patterns. Semistructured interviews were conducted with them about their solutions. The data were analyzed by using the PirieKieren theory of mathematical understanding. The findings of this study revealed that students’ mathematical
understanding varied between first six levels from primitive knowing to observing and their mathematical
understanding mostly occurred between Image Making and Formalising layers. In terms of theory, students were
able to pass the first and second “Don’t Need” boundaries but they could not progess their understanding over the
third “Don’t Need” boundary. The results also illustrated that all of the students had knowledge about the patterns.
In order to find the general rule of the pattern, they mostly endeavored to determine a formula and check its
correctness by writing initial three steps.