#### Number Sense

#### Classification & Patterns

Number and Operations in Base Ten

An important understanding develops in first grade: that 10 ones make a ten – a unit that is a bundle of 10 ones. Students learn to compose and decompose numbers – put them together and take them apart – in different ways. This helps their understanding of the “teen” numbers (11, 12, 13, 14, 15, 16, 17, 18, and 19) as a ten and some ones.

In first grade, students compare numbers using the words more than, less than, greater than, most, greatest, least, same as, equal to, and not equal to; as well as the symbols <, >, =. They realize that the digit in the tens place is more important than the digit in the ones place when comparing two numbers. For example 51 is more than 29, even though when you look at the ones digits it appears to be the opposite.

This illustration represents 14 by showing one 10 and 4 ones.

Operations and Algebraic Thinking

(Classification & Patterns)

Grade one students develop an understanding of addition and subtraction of numbers that result in answers no larger than twenty. Students use strategies to add and subtract within 20. These strategies may include putting together (composing) and taking apart (decomposing) numbers to get the answer. They are fluent with addition and subtraction that result in answers to ten.

Students in first grade are able to represent word problems (e.g., using objects, drawings, and equations) and explain the method they used to solve addition and subtraction word problems within 20.