This Grade 9-10 Math Decision Support Tool is designed to help students self-assess their understanding of the skills and concepts learned in Grade 9 math that are most important to understand prior to entering Grade 10 math (MPM2D). This tool is designed for students to check their own understanding using a sliding scale and associated questions, organized by specific math topics. This tool is an overview of core concepts from Grade 9 math and is not an exhaustive list of all concepts taught. This tool is not intended to be completed in its entirety or to be used as a test, but rather as a manageable way for students to identify their own understanding of key mathematical concepts to help inform their course choice in Grade 10.