1.PAFR.1: Understand and apply properties of operations and the relationship between addition and subtraction to solve problems.

Understand and apply properties of operations and the relationship between addition and subtraction to solve problems.

1.PAFR.1.1Determine and explain if an equation within 10 is true using a variety of equation formats.1.PAFR.1.2Compose and decompose numbers less than or equal to 20 in more than one way. Record each composition or decomposition as an equation.1.PAFR.1.3Solve add-to, take-from, and part-part-whole real-world situations to find sums and differences within 20. Situations include result or change unknown, both addends unknown, and total or one part unknown.1.PAFR.1.4Add and subtract number combinations flexibly and accurately within 10.1.PAFR.1.5Apply and explain the Commutative Property of Addition to find the sum (through 20) of the two addends and explain that the value does not change when the order of the two numbers changes.1.PAFR.1.6Determine an unknown number in addition and subtraction equations within 10.1.PAFR.1.7Find the sum of a two-digit number and a one-digit number or a two-digit number and a multiple of 10 (1–99) using concrete models, drawings, and strategies that reflect place value understanding, the inverse relationship of addition and subtraction, and the properties of the operations to justify the sum.1.PAFR.1.8Find the difference between two numbers that are multiples of 10, both in the range 10–90, and write the corresponding equation. Explain the reasoning used.

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