In February 2019, APQC K-12 Education interviewed Christ Church Grammar School (CCGS) to discuss their recent school improvement initiative that has revamped how they manage assessments. These successes were due to exposure of a systematic process and change management approach. CCGS reviewed its methods for differentiated assessment, and realized they had weaknesses within the practices. They found inconsistency in students' assessments within and between year levels and that the assessment results did not consistently correlate with the students' standardized testing proficiencies. The need came for improvement to its assessments and reporting processes and methods to better differentiate instruction for students as well as better leverage teachers’ time. This case study discusses how the results of their improvement initiatives are impacting students' progression and how teachers can now accurately track and measure that progression.