Beginning in third grade, Pennsylvania students are required to take the Pennsylvania State Standardized Assessment (PSSA), which presents multiple-choice mathematics questions and open-ended mathematics problems. Consistent with the Communication Standard of the National Council of Teachers of Mathematics, while solving the open-ended problems, students must explain and describe the process they follow to arrive at their answer. This article discusses a student-friendly math rubric that helped improve third graders' competencies when explaining solution strategies in writing. It describes a third-grade teacher's story about her action research project and what she learned about using the math rubric with elementary school children. (Contains 7 figures.)