After 18 years of teaching IB and IGCSE Computer Science, I kept seeing the same pattern: students plateau not from lack of effort, but because a lost mark is never explained. It's a concept gap, a misread question, or the wrong format, each needing a different fix. Unable to give that attention by hand across Years 9–12, I built ExamEdge worksheets to diagnose why marks are lost, the way I always did in class.