Grade 2 - Number
Standard 2.N.2 - Practice subtracting objects from 1 to 10.
Included Skills: Subtraction
Demonstrate understanding of addition (limited to 1 and 2-digit numerals) with answers to 100 and the corresponding subtraction by: • representing strategies for adding and subtracting concretely, pictorially, and symbolically • creating and solving problems involving addition and subtraction • estimating • using personal strategies for adding and subtracting with and without the support of manipulatives • analyzing the effect of adding or subtracting zero • analyzing the effect of the ordering of the quantities (addends, minuends, and subtrahends) in addition and subtraction statements. • Generalize rules for adding when one addend is zero and for subtracting zero from a quantity and use concrete, pictorial, physical, or oral models to explain the reasoning. • Verify rules generalized for addition and subtraction involving a quantity of zero. • Model concretely, pictorially, or physically situations that involve the addition or subtraction of 1 and 2-digit numbers (with answers to 100) and explain how to record the process shown in the model symbolically. • Generalize and apply strategies for adding and subtracting 1 and 2-digit numbers (with answers to 100). • Create, model symbolically (and concretely, pictorially, or physically if desired), and solve addition and subtraction problems related to situations relevant to one's self, family, or community. • Critique the statement "You can add or subtract numbers in any order and still get the same answer" and provide examples to support the critique. • Select and explain a mental mathematics strategy that can be used to determine a sum of up to 18 (or related difference): - doubles (e.g., for 4 + 6, think 5 + 5) - doubles plus one (e.g., for 4 + 5, think 4 + 4 + 1) - doubles take away one (e.g., for 4 + 5, think 5 + 5 - 1) - doubles plus two (e.g., for 4 + 6, think 4 + 4 + 2) - doubles take away two (e.g., for 4 + 6, think 6 + 6 - 2) - making 10 (e.g., for 7 + 5, think 7 + 3 + 2) - building on a known double (e.g., 6 + 6 = 12, so 6 + 7 = 12 + 1 = 13).