ABSTRACT
The mathematics classroom is a complex environment in which multiple things happen simultaneously. Teachers cannot possibly attend to all this richness equally; they must learn to filter through that complexity and decide where to place their instructional attention and efforts. A crucial part of teaching, then, involves observing the classroom and choosing and making sense of those aspects of the class that are pedagogically relevant. This book as a whole and the individual chapters within it are all predicated on the belief that this process-what has been called noticing-is a key component of teaching expertise and of mathematics teaching expertise in particular.
