Education reform in the United States since the 1980s has been largely driven by the setting of academic standards for what students should know and be able to do. These standards can then be used to guide all other system components. The SBE (standards-based education) reform movement calls for clear, measurable standards for all school students. Rather than norm-referenced rankings, a standards-based system measures each student against the concrete standard. Curriculum, assessments, and professional development are aligned to the standards.