Lesson study is a time-tested approach to professional learning that exemplifies the Standards for Professional Learning: It is ongoing and sustained, embedded in classroom practice, focused on student outcomes, and occurs in professional learning communities. In this approach, teachers collaboratively observe and discuss classroom lessons by analyzing data they collect related to teaching and learning. Developed and initially practiced in Japan, lesson study has been used for decades. This recent study from researchers in the United Kingdom and the Netherlands adds to a growing research base that suggests a positive impact of lesson study and contributes to an international body of evidence that professional learning improves teacher practice. A learning patterns perspective In lesson study, a team of teachers collaboratively decide on a focal lesson.