The teacher displayed counting cards that included both dots and numerals in order from one to five, as she counted them with her students. She then turned the cards facedown, keeping them in order, and began an identify-a-hidden-card activity with the class. This class was engaged in the third of three card activities that develop number sense and number skills. In this article, the authors describe how they have used and modified this activity both to develop mathematical competencies and to develop important higher-order, or executive function, skills. They conclude by providing strategies for modifying any mathematics activity to similarly get "double impact"--simultaneous development of young children's mathematical proficiencies and executive function skills.