#### Number Sense

##### In first grade, students viewed two-digit numbers as amounts of tens and ones. A critical area of instruction in grade two is to extend students’ understanding of base-ten notation or place value, to include hundreds. Second-grade students understand multi-digit numbers (up to 1,000). They add and subtract within 1,000 and become fluent with addition and subtraction within 100 using place-value strategies.

Second-grade students build on their previous work with groups of tens to make bundles of hundreds, using base-ten blocks, cubes in towers of 10, 10-frames, and so forth. After sufficient experience with the hands-on materials, students can draw these shapes, showing 10 ones together as 1 ten, and 10 tens together as 1 one-hundred.

Students explore the idea that numbers such as 100, 200, 300, and so on are groups of hundreds that have “0” in the tens and ones places. Students might represent numbers using place-value (base-ten) blocks or math drawings.