Sequences are an important topic--not only in mathematics but also in the mathematics curriculum. Exploring sequences related to medial triangles offers learners opportunities to solve problems involving sequences within geometric contexts. Sequences related to medial triangles are also a rich source of beautiful and interesting geometric patterns…

This case study investigates prospective middle school mathematics teachers' use of the Angle tool in GeoGebra, focusing on reflex angles in a geometric construction task. They constructed a parallelogram with individual heights for any two consecutive sides. We analyzed their screencasts to identify the ways in which they used reflex angles in…