In This Unit of Study…

Students add and subtract within 100 with procedural fluency.  Strategies are based on place value, properties of operations, and the relationship between addition and subtraction.  Students will use concrete models and drawings to add and subtract two whole numbers within 1,000.  Students determine and explain whether equations involving addition and subtraction are true or false.  In addition, students will extend the development of algebraic thinking skills by determining the unknown whole number in addition or subtraction equations, with the unknown in any position. Students will continue work with multi-digit addition and subtraction in the next scope/unit.

B.E.S.T. Benchmarks:

• MA.2.NSO.2.3 Add two whole numbers with sums up to 100 with procedural reliability. Subtract a whole number from a whole number, each no larger than 100, with procedural reliability.
• MA.2.NSO.2.4 Explore the addition of two whole numbers with sums up to 1,000. Explore the subtraction of a whole number from a whole number, each no larger than 1,000.
• MA.2.AR.2.1 Determine and explain whether equations involving addition and subtraction are true or false.
• MA.2.AR.2.2 Determine the unknown whole number in an addition or subtraction equation, relating three or four whole numbers, with the unknown in any position.

Key Concepts:

• I can choose a method I can use reliably to add two whole numbers with sums up to 100.
• I can choose a method I can use reliably to subtract a whole number from a whole number within 100.
• I can use manipulatives, number lines, drawings, or properties of operation or place value to explore the addition of two whole numbers up to 1,000.
• I can use manipulatives, number lines, drawings, or properties of operation or place value to explore the subtraction of two whole numbers up to 1,000.
• I understand that it is necessary to compose and decompose ones, tens, and hundreds when needed to add or subtract within 1,000.
• I can determine and explain whether equations involving addition and subtraction are true or false within 100 in equations with three or four terms with the unknown on either side of the equal sign.
• I can determine the unknown whole number in an addition equation, relating three or four whole numbers, with the unknown in any position.
• I can determine the unknown whole number in a subtraction equation, relating three or four whole numbers, with the unknown in any position.