Graded Troubleshooting (GTS) is a powerful routine that teachers can use easily to engender students' metacognitive thinking and boost their understanding of mathematics concepts and procedures. This article describes a new GTS activity designed to prompt students to efficiently exploit worked examples when asked to diagnose erroneous examples containing typical procedural errors related to exponents. The GTS activity, its implementation in ninth-grade classes studying exponents, and a practical guide for teachers on ways to construct and implement GTS are presented below.