In this study, we investigated mathematics teacher's noticing of students' thinking in the context of mathematical modeling activities (MEAs) related to statistics. One middle-school mathematics teacher participated in the study, which adopted a case study design. Data were collected through interviews with the teacher based on video recordings of students' group work, the written works of the students, and the researchers' observations and field notes. As students evolved from first-draft solutions to more powerful, sharable ways of thinking about the modeling activity, the teacher focused on student thinking related to four distinct aspects of the overall modeling activities: understanding the problem, manipulation, interpretation, and verification. She mostly focused on procedural aspects of students' thinking during the manipulation step. Her attention and interpretation of the manipulation step focused on the students' (a) identification of the solution (how students reach the solution), (b) reasons why they selected these solutions (explanations and justifications of the solutions), and (c) features of the solutions they used. The teacher also noticed how the students' performances depended on the structure of the activity (whether a data set was given). She pointed out that MEAs support students' engagement, conceptual understanding, skills related to statistics, and ability to use data processing concepts in their daily lives.