Learning cards set provides a variety of ways to let your students practice and reinforce important math skills. Grade-level appropriate math problems help students develop a better understanding of subtraction. Double-sided cards provide a perfect way for students to practice subtracting numbers horizontally and vertically, whole numbers, single-digit numbers and double-digit numbers. Cards are compatible with the Teacher Created Resource Power Pen (sold separately) for immediate feedback with an audio and visual response. Set is designed for children attending kindergarten to second-grade.