Rhymed prose (manẓūma) was sometimes used in the medieval Arabic pedagogical context. The rhythmical and rhymed characteristics helped students to memorize more efficiently. The genre was especially popular for introductory treatises which provided the basic foundational knowledge in various fields and which were intended to be memorized by students. Examples of manẓūma are not unknown in mathematics [G. Shawki, “Manẓumāt al-`ilm al-riyāḍī,” Ḥawliyat Kulliyat al-Insāniyāt wa-l-`Ulūm al-Ijtimā`iya, 7 (1984), 187-235], although they have received relatively little scholarly attention because they rarely contain the innovative mathematics that historians traditionally emphasized. In this paper, I examine, as an example of the genre, a previously unstudied manẓūma (Tehran, Majlis Shura 5074) based on a specific mathematical treatise – the Ashkāl al-Ta’sīs, an introduction to geometry by Shams al-Dīn al-Samarqandī (died 701 A.H. / A.D. 1302). This treatise, one of the most influential geometry textbooks of the medieval period, continued to be copied, studied, and commented upon until the nineteenth century. My paper falls naturally into two parts: (1) an introduction to the genre of rhymed mathematical prose, (2) a comparison of the contents of the manẓūma with the original mathematical exposition of the Ashkāl al-Ta’sīs. Here I assess the effectiveness of rhymed prose for mathematical exposition. What elements of the original treatise had to be sacrificed? Can technical vocabulary be incorporated effectively into rhymed prose? Can diagrams be incorporated effectively into rhymed prose?