The Holy Cross School first graders began the addition and subtraction unit by adding and subtracting ten to 2-digit numbers. The children used base-10 blocks, drawings, and number lines to numerals within 100. (22+ 10=32). The pupils then developed the process of adding and subtracting multiple tens to a 2-digit number using base-10 blocks and partial sum or difference algorithms. (42-30=12). The students read and interpreted charts and graphs to determine if they should add and subtract 2-digit numbers. To continue the addition and subtraction lessons, the students learned how to read real word problems to determine what the best mathematic equations to solve the problems. The students practice reading words such as put together, take apart, and how many in all.