The ability to recognize and construct nets is a fundamental aspect of spatial reasoning skills; however, there is a lack of understanding regarding effective instructional sequences for fostering this ability. The aim of this study is to test a Hypothetical Learning Trajectory for enhancing sixth-grade students' understanding of rectangular prism nets. Conducted over four weeks, this teaching experiment involved 12 sixth-grade students from a public school in Turkey, selected based on varying mathematics achievement levels. Data were collected through clinical interviews, video recordings, and student worksheets. Ongoing and retrospective analyses were employed to describe students' understanding during the implementation of HLT. The findings detail the results of the teaching experiment and the HLT verified following the experiment. This study contributes to the existing research on students' understanding of rectangular prism nets and provides valuable insights for mathematics educators aiming to design effective instructional sequences that promote spatial reasoning skills.