The potential of a theory of variation-framed learning study, a teacher professional development approach, to help teachers overcome curricular and pedagogical challenges associated with teaching new science curricula content was explored. With a group of Singapore teachers collaboratively planning and teaching new genetics content, phenomenographic analysis of data corpus from classroom observations, teacher meetings and interviews revealed teacher learning that manifested in the teachers' experiences. These were captured as (1) increased degrees of student-centered pedagogy and challenges to teachers' prior assumptions about science pedagogy, (2) increased awareness of possibilities and limitations of their beliefs about science pedagogy, and (3) emergence of new understandings about new curricular content and science pedagogy. The possibility of transformative and generative learning is also discussed.