## Addition and Subtraction Word Problems

Represent and solve addition and subtraction word problems, within 20, with unknowns, by using objects, drawings, and equations with a symbol for the unknown number to represent the problem, when solving: • Add to/Take from-Change Unknown • Put together/Take Apart-Addend Unknown • Compare-Difference Unknown

## Adding and Subtracting within 20

NC.1.OA.4 Solve an unknown-addend problem, within 20, by using addition strategies and/or changing it to a subtraction problem. NC.1.OA.6 Add and subtract, within 20, using strategies such as counting on, making ten, decomposing a number leading to a ten, using the relationship between addition and subtraction, using a number line, and creating equivalent but simpler or known sums. NC.1.OA.9 Demonstrate fluency with addition and subtraction within 10.

## Number Sentences

NC.1.OA.7 Apply understanding of the equal sign to determine if equations involving addition and subtraction are true. NC.1.OA.8 Determine the unknown whole number in an addition or subtraction equation involving three whole numbers.

## Number Sentences

###### NC.1.OA.78

Represent and solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, by using objects, drawings, and equations with a symbol for the unknown number.

## Properties of Operations

Apply the commutative and associative properties as strategies for solving addition problems.

## Length of an Object

Measure lengths with non-standard units. • Express the length of an object as a whole number of non-standard length units. • Measure by laying multiple copies of a shorter object (the length unit) end to end (iterating) with no gaps or overlaps.

## Ordering Objects by Length

Order three objects by length; compare the lengths of two objects indirectly by using a third object.

## Tell and Write Time

Tell and write time in hours and half-hours using analog and digital clocks.

## Interpreting Data

Organize, represent, and interpret data with up to three categories. • Ask and answer questions about the total number of data points. • Ask and answer questions about how many in each category. • Ask and answer questions about how many more or less are in one category than in another.

## Tens & Ones

Understand that the two digits of a two-digit number represent amounts of tens and ones. • Unitize by making a ten from a collection of ten ones. • Model the numbers from 11 to 19 as composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. • Demonstrate that the numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens, with 0 ones.

## Comparing Numbers

Compare two two-digit numbers based on the value of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.

## Comparing Numbers

###### NC.1.NBT.3

Using concrete models or drawings, strategies based on place value, properties of operations, and explaining the reasoning used, add, within 100, in the following situations: • A two-digit number and a one-digit number • A two-digit number and a multiple of 10

## Subtract Multiples of 10

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90, explaining the reasoning, using: • Concrete models and drawings • Number lines • Strategies based on place value • Properties of operations • The relationship between addition and subtraction

## Mental Math

Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

## Partitioning Into Equal Shares

Partition circles and rectangles into two and four equal shares. • Describe the shares as halves and fourths, as half of and fourth of. • Describe the whole as two of, or four of the shares. • Explain that decomposing into more equal shares creates smaller shares.

## Shape Attributes

Distinguish between defining and non-defining attributes and create shapes with defining attributes by: • Building and drawing triangles, rectangles, squares, trapezoids, hexagons, circles. • Building cubes, rectangular prisms, cones, spheres, and cylinders.

## Composite Shapes

Create composite shapes by: • Making a two-dimensional composite shape using rectangles, squares, trapezoids, triangles, and half-circles naming the components of the new shape. • Making a three-dimensional composite shape using cubes, rectangular prisms, cones, and cylinders, naming the components of the new shape.