Commentary on two classroom observation systems: moving toward a shared understanding of effective teaching.

In this commentary, I make five points: that designing observation systems that actually predict students' outcomes is challenging; second that systems that capture the complex and dynamic nature of the classroom learning environment are more likely to be able to meet this challenge; three, that observation tools are most useful when developed to serve a particular purpose and are put to that purpose; four that technology can help; and five, there are policy implications for valid and reliable classroom observation tools. The two observation systems presented in this special issue represent an important step forward and a move toward policy that promises to make a true difference in what is defined as high quality and effective teaching, what it looks like in the classroom, and how these practices can be more widely disseminated so that all children, including those attending under-resourced schools, can experience effective instruction, academic success and the lifelong accomplishment that follows.