Kansas Academic Standards
KS.2.OA. Operations and Algebraic Thinking
Add and subtract within 20.
2.OA.2. Fluently (efficiently, accurately, and flexibly) add and subtract within 20 using mental strategies (counting on, making a ten, decomposing a number, creating an equivalent but easier and known sum, and using the relationship between addition and subtraction). Work with equal groups of objects to gain foundations for multiplication.
KS.2.NBT. Number and Operations in Base Ten
Understand place value.
2.NBT.1. Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones; (e.g. 706 equals 7 hundreds, 0 tens, and 6 ones.) Understand the following as special cases:
2.NBT.1c. Show flexibility in composing and decomposing hundreds, tens and ones (e.g. 207 can be composed from 2 hundreds 7 ones OR 20 tens 7 ones OR 207 ones OR 1 hundred 10 tens 7 ones OR 1 hundred 9 tens 17 ones, etc.)
Use place value understanding and properties of operations to add and subtract.
2.NBT.5. Fluently (efficiently, accurately, and flexibly) add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction (e.g. composing/decomposing by like base-10 units, using friendly or benchmark numbers, using related equations, compensation, number line, etc.).
2.NBT.6. Add up to four two-digit numbers using strategies based on place value and properties of operations.
2.NBT.7. Add and subtract within 1000, 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. Understand that in adding or subtracting three-digit numbers, like base-ten units such as hundreds and hundreds, tens and tens, ones and ones are used; and sometimes it is necessary to compose or decompose tens or hundreds.
2.NBT.9. Explain why addition and subtraction strategies work using place value and the properties of operations. The explanations given may be supported by drawings or objects.