# Module 1

### Sums and Differences to 10

## Standards

1.OA.A.1: Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

- I can use a symbol (e.g. ?, x) to represent an unknown number in a problem.
- I can determine the operation to solve word problems with unknowns.
- I can solve word problems by adding 3 numbers in different ways.

1.OA.B.3: Apply properties of operations as strategies to add and subtract. Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)

- I can explain how properties of addition and subtraction work.
- I can use strategies to solve addition and subtraction problems.

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.

- I can identify the unknown in a subtraction problem.
- I can solve subtraction problems to find the missing addend.
- I can explain the relationship of addition and subtraction.

1.OA.C.5: Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

- I can count on from a given number.
- I can count back from a given number.
- I can explain how counting on relates to addition.
- I can explain how counting back relates to subtraction.
- I can explain how counting on relates to subtraction.

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).

- I can add within 20.
- I can subtract within 20.
- I can use strategies to add and subtract within 20.
- I can add fluently within 10.
- I can subtract fluently within 10

1.OA.D.7: Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

- I can explain the meaning of an equal sign.
- I can compare the values on each side on an equal sign.
- I can determine if the equation is true or false.

1.OA.D.8: Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = – 3, 6 + 6 = .

- I can recognize part-part-whole relationships of three numbers
- I can determine the missing value in an addition equation.
- I can determine the missing value in a subtraction problem

### The following resources are meant to be used in conjunction with our core curriculum. They are NOT meant to replace it. These materials are to give students additional practice on the mathematical concepts covered in this Module.

## Anchor Charts

## Strategies

1.OA.1

1.OA.3

1.OA.4

1.OA.8