Assessment of learning refers to assessment that occurs at the end of a learning unit and results in a number or letter grade. It compares a student's achievement to standards and communicates results to students and parents. The document outlines guiding principles for assessment of learning, including that it should be an integral part of teaching, use assessment tools that match learning objectives, provide feedback to students, consider learning styles, emphasize self-assessment and real-world application over drill items, and communicate results regularly to parents. Assessment should occur prior to, during, and after instruction using various tools like tests, performances, and portfolios.