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Lesson plan

Subtract within 20 by subtracting in parts

teaches Common Core State Standards 2.OA.B.2 http://corestandards.org/Math/Content/2/OA/B/2

Subtract within 20 by subtracting in parts

Big Idea: Numbers can be decomposed and recombined different ways to add and subtract. Therefore, there are many solutions to the same problem. This lesson builds on students' understanding of composing and decomposing numbers as strategies to add and subtract. The task asks for students to think about how numbers can be decomposed and subtracted multiple ways as a strategy for subtraction. Vocabulary: add, subtract, equation, decompose, equal, value Special Materials: Connecting Cubes