This article is intended to contribute to greater knowledge regarding the importance of flow and the time used to perform an activity, with a focus on students' mathematical experiences of 3D bodies. Thirty-one 9th-grade students took part in the study. Flow and variation theory was used in the analysis of lesson observations, submission tasks, audio recordings, logbooks, tests and nationwide tests. The results indicate that the selected mathematics problem is characterized by seven components, which serve as the basis for identifying intended critical aspects; a variation is evident in the balance between skills and challenges that is characterized by the critical aspects that the students discern; a variation is evident in the experience of flow that is dependent upon the students' approach to their work on various activities; the students' mathematical experiences are based, both short- and long-term, on discerned critical aspects and on the time spent on the activity that generates flow. Theoretical contributions as well as implications for teaching are presented at the end of the article.