Navvy (rhymes with "savvy") is an evidence-based, standards-level assessment system that helps leaders, teachers, and students navigate learning by providing on-going, real-time diagnoses of standards mastery using cutting-edge, research-proven data science. This data science is unique to Navvy and enables feedback to be reliable for individual standards while keeping the assessments short. As a result, Navvy supports personalized learning by pinpointing which standards students understand and which standards they still need to help to understand. This actionable information can be used to inform meaningful groups of students for targeted instruction and support learning for each child. Navvy assessments are on-demand, and users decide when to assess and which standards to assess. Assessment questions were specifically designed for the Navvy diagnostic system and authored by educators with extensive classroom experience and top-notch expertise.