# Subtracting Like Ninjas

If you’re wondering what the Common Core State Standards (CCSS) are for Math in Grade 2, I’ve pasted information from the CCSS website below.  It uses parent-friendly verbiage and provides a broad over-view of the expectations.

Students are currently learning how to subtract 3-digit numbers (to the hundreds place) with and without re-grouping.  Now that they’re getting good at it, we took time today to make a little project.  We made Ninjas holding a math problem showcasing their math skills.  We made Ninjas because Math Ninjas are known to be quick, swift, skilled, knowledgeable, and they don’t have to use their fingers to subtract AND they know the next step to solve a problem without thinking first . . . they just do it!

Check out the pictures! http://www.corestandards.org/Math/Content/2/introduction/

In Grade 2, instructional time should focus on four critical areas: (1) extending understanding of base-ten notation; (2) building fluency with addition and subtraction; (3) using standard units of measure; and (4) describing and analyzing shapes.

1. Students extend their understanding of the base-ten system. This includes ideas of counting in fives, tens, and multiples of hundreds, tens, and ones, as well as number relationships involving these units, including comparing. Students understand multi-digit numbers (up to 1000) written in base-ten notation, recognizing that the digits in each place represent amounts of thousands, hundreds, tens, or ones (e.g., 853 is 8 hundreds + 5 tens + 3 ones).
2. Students use their understanding of addition to develop fluency with addition and subtraction within 100. They solve problems within 1000 by applying their understanding of 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. They select and accurately apply methods that are appropriate for the context and the numbers involved to mentally calculate sums and differences for numbers with only tens or only hundreds.
3. Students recognize the need for standard units of measure (centimeter and inch) and they use rulers and other measurement tools with the understanding that linear measure involves an iteration of units. They recognize that the smaller the unit, the more iterations they need to cover a given length.
4. Students describe and analyze shapes by examining their sides and angles. Students investigate, describe, and reason about decomposing and combining shapes to make other shapes. Through building, drawing, and analyzing two- and three-dimensional shapes, students develop a foundation for understanding area, volume, congruence, similarity, and symmetry in later grades.