Learning progression is a research area that focuses on understanding how students develop their knowledge and skills over time in a specific subject area. It examines the sequence of learning milestones and the conceptual understanding that students acquire as they progress through different grade levels or stages of their education. Learning progression research also explores the factors that influence students' learning trajectories, such as prior knowledge, teaching methods, and instructional materials. By identifying the key concepts and skills that students should master at each stage of their education, learning progression research aims to inform curriculum development, assessment practices, and instructional strategies to support more effective and meaningful learning outcomes.