## ◂Math Worksheets and Study Guides First Grade. One Less, One More

### The resources above correspond to the standards listed below:

#### South Dakota Content Standards

1.OA. Operation and Algebraic Thinking
1.OA.B. Understand and apply properties of operations and the relationship between additions and subtraction.
1.OA.B.4. Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
1.OA.C. Add and Subtract with in 20.
1.OA.C.6. Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
1.NBT. Number and Operation in Base Ten
1.NBT.A. Extend the counting sequence.
1.NBT.A.1. In the range of 0 - 120
1.NBT.A.1.a. Count on from any given number.
1.NBT.C. Use place value understanding and properties of operation to add and subtract
1.NBT.C.4. Add and subtract within 100.
1.NBT.C.4.a. Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
1.NBT.C.4.b. Understand that in adding two-digit numbers (sums within 100) add tens and tens, ones and ones; and sometimes it is necessary to compose a ten.