Textbooks greatly influence teaching practice. A teacher using one textbook may be more likely to cover many topics, spend one day on topic, use a teacher-directed instructional approach, and focus on procedures. Using a different textbook ( that is more standards-based), a teacher may devote more time to a concept, teach it more deeply, and use a student-centered approach. Writing, speaking, working in groups, and problem solving are more likely to be commonplace components in current curriculum offerings. The selection of curriculum materials is an important endeavor.