Teacher noticing can be an important element in improving teaching and students' mathematical success. While the focus of the international project "Learning from Lessons" was on teacher learning, in this paper we report what mathematics teachers noticed and claimed to learn through the process of planning, teaching, and reflecting on their lessons. The study involved teachers and research teams from three countries (Australia, China and Germany) with different cultures, contexts and pedagogies. The explicit goal of the current study was to identify commonalities and differences with respect to those aspects that teachers noticed during their teaching. A multiple case study with three teachers, one from each of the three participating countries, was conducted using prompting questions to facilitate teacher reflection. The process of defining and refining categories for teacher noticing was implemented in the methodology. The findings suggest that there were many commonalities across the cases despite the different cultural and individual backgrounds of the teachers. The specific topic and individual lessons as well as the teachers' expectations based on their lesson planning seemed to influence what the teachers noticed in their teaching process. The study highlights the importance of attending to the situational aspects of teacher noticing and learning.