Curriculum design models provide a framework for educators to plan learning experiences and assessments that help students develop a deeper understanding of concepts. These models incorporate goals, student needs, resources, and evaluation methods. They recognize that simply following a textbook is not enough in the 21st century, where students must learn to apply knowledge in new contexts. Research shows curriculum should be learner-centered, knowledge-centered, and assessment-centered. One prominent model, Understanding by Design, involves identifying important learning outcomes, determining how understanding will be demonstrated over time through various assessments, and then planning instruction accordingly.