The Russian School of Mathematics-Winchester, an after-school math program for students in kindergarten through grade 12, will host its grand opening from 11 a.m. to 4 p.m. Saturday. According to principal Maria Gofshteyn, the school will celebrate the unveiling of its newly refurbished building at 50 Cross St., which had been vacant for more than a decade, with a number of activities and performances. Throughout the day, free math evaluations will be offered to new students and math games and logic puzzles will be available for parents and students. Students from the program will perform, showcasing their talents in art, music, sport, and dance. A math competition will take place between two of the program’s third-grade classes. Later in the day, program students will be pitted in a math competition against their parents. Inessa Rifkin, the program’s chief executive officer, will speak about the importance of being prepared for tracking in middle school. For more information, visit www.russianschool.com/winchester-grand-opening.