In order for mathematical experiences such as those described in this section to happen frequently, the teacher must establish the expectation that the class as a mathematical community is continually developing, testing, and applying conjectures about mathematical relationships. In the episode in Ms. Taylor's third-grade classroom, where students explored the effects of multiplying by 2 and by 2 again, the teacher looked for an opportunity to go beyond finding the solution to an individual problem to focus on more-general mathematical structures and relationships. In this way, she helped her students recognize reasoning as a central part of mathematical activity.