groups such as minorities and women. This principle encourages provision of extra help to students who are struggling and advocates high expectations and excellent teaching for all students. Curriculum: In the PSSMs curriculum section, the NCTM promotes a "coherent" curriculum, in which an orderly and logical progression increases students' understanding of mathematics and avoids wasting time with unnecessary repetition. They acknowledge that the relative importance of some specific topics changes over time. For example, a basic understanding of iteration is important to students who are learning computer programming, and is almost absent from 19th century textbooks. Similarly, older American math textbooks included lessons that are no longer considered important, such as rules for calculating the number of bushels of hay that could be stored in a bin of stated dimensions, because this skill was useful to farmers at that time. The NCTM proposes that mathematics taught in modern classrooms be the skills that are most important to the students' lives and careers. Teaching: In the PSSM, the NCTM promotes sound teaching methods, without prescribing a one-size-fits-all approach. The NCTM wants teachers to be able to use their professional judgment in choosing teaching techniques. They favor professional development opportunities in both mathematics (content) and in effective teaching techniques (methods). Learning: According to the PSSM, a combination of "factual knowledge, procedural facility, and conceptual understanding" is necessary for students to use mathematics. While they state that "learning the 'basics' is important", the NCTM does not consider the most simplistic forms of memorization by repetition to be sufficient achievement in mathematics. A good student not only understands how and when to use facts, procedures, and concepts, but he or she also wants to figure things out and perseveres in the face of challenge. The NCTM particularly deprecates attitudes in schools that suggest only certain students are capable of mastering math. Assessment Technology Standards Ten general strands or standards of mathematics content and processes were defined that cut across the school mathematics curriculum. Specific expectations for student learning, derived from the philosophy of outcome-based education, are described for ranges of grades (preschool to 2, 3 to 5, 6 to 8, and 9 to 12). These standards were made an integral part of nearly all outcome-based education and later standards-based education reform programs that were widely adopted across the United States. Content standards Number and Operations: These are the fundamental basis of all mathematics, and