\input zb-basic \input zb-matheduc \iteman{ZMATH 2012f.01096} \itemau{Fern\'andez, Ceneida; Llinares, Salvador; Valls, Julia} \itemti{Learning to notice students' mathematical thinking through on-line discussions.} \itemso{ZDM 44, No. 6, 747-759 (2012).} \itemab Summary: The goal of this research is to characterize prospective mathematics teachers' development of professional noticing of students' mathematical thinking in on-line contexts. Specifically, we are interested in how the participation in on-line discussions, when prospective teachers solve specific tasks, supports the development of professional noticing of students' mathematical thinking. Findings show that an aspect in which the on-line discussions, as an example of asynchronous collaborative communication interfaces, support this development is related to the role of writing; participating in an on-line discussion plays a significant role since the final written text is functional as regards the activity of interpreting students' mathematical thinking collaboratively. \itemrv{~} \itemcc{U50 C30 D60} \itemut{on-line learning environments; dialogic argumentation; professional noticing; students' mathematical thinking} \itemli{doi:10.1007/s11858-012-0425-y} \end