An excellent mathematics program requires effective teaching to engage students in meaningful learning that promotes their ability to make sense of mathematical ideas and reason mathematically. How? By implementing sound research-based guiding principles for school mathematics. Effective teaching and learning occurs when there are clear mathematical goals. In the classroom this can mean implementing tasks that promote reasoning and problem solving, using and connecting different mathematical representations, and facilitating meaningful mathematical discourse through purposeful questioning. Supporting productive struggle in learning mathematics and using evidence of student thinking are also essential. This professional resource explores these principles (and others), and identifies the inevitable obstacles that need to be solved when attempting change. A clearly written and accessible volume from the respected National Council of Teachers of Mathematics in the United States.