In second grade, students extend their understanding of the base-ten system. Students understand multi-digit numbers up to 1,000 written in base-ten notation, recognizing that the digits in each place represent amounts of thousands, hundreds, tens, or ones. Students use their understanding of addition to develop fluency with addition and subtraction within 100. They solve problems within 1,000 applying their models for addition and subtraction, and they develop, discuss, and use efficient, accurate, and generalizable methods to compute sums and differences of whole numbers in base-ten notation, using their understanding of place value and the properties of operations. Second grade students also use rulers and other measurement tools and investigate, describe, and reason about decomposing and combining shapes to make other shapes.
Link to CC Standards for Math: http://www.corestandards.org/Math/Content/2/introduction/