Math Flash Cards for Children - Printable PDF. Math flash cards for children in Preschool, Kindergarten, 1 st, 2 nd, 3 rd, 4 th, 5 th, 6 th and 7 th grades created with Common Core State Standard in mind. Each set of cards has 32 cards and 32 problems to solve. These flash cards can be used to play any math classroom game and methods of using ...