This chapter begins with a discussion of mathematics teaching as a profession by examining trends in mathematics education over time and by evaluating various national and international assessments of student achievement. Mr. James values the exploration of student ideas and entered the teaching profession not only because he enjoyed mathematics but also because he was excited about having the chance to work with adolescents at a critical time in their development as students and young adults. In 1995, the most comprehensive international comparison of mathematics education in history was conducted. Substantial differences were identified when teachers’ presentations of new content, difficulty level of mathematics problems posed by teachers, and teachers’ handling of classwork and homework were considered. Ideally, in the contemporary view of mathematics, every lesson should include some opportunity for students to refine their problem-solving skills. When students are pressed to defend their thinking, it helps them to develop a fuller understanding of the underlying mathematics.