Successful learning is brought about by an interaction of a lot of factors. One important factor is what the learners already possess before a new learning experience begins. Evidences from a physical science class about the significant learner-related factors that could explain why students are successful or unsuccessful in performing assessment tasks are presented in this book. It also addresses some important issues in selecting assessment tasks; designing cognitive structures to ensure that learning can occur while students are being assessed; and developing, validating and testing the reliability of rubrics. Samples of assessment tasks including student and teacher rubrics are incorporated in this book. These are tools that can be used in checking the students' concepts and understanding while assessment and learning are going on simultaneously.