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Math: Introducing 2-Digit Addition and Subtraction Strategies

Suggested Time Frame: 20 Instructional Days


Focus TEKS

Adding and Subtracting within 100

  • Computation
    • 2.4B add up to four [two in this unit] two-digit numbers and subtract two-digit numbers using mental strategies and algorithms based on knowledge of place value and properties of operations
      • 2.2A use concrete and pictorial models to compose and decompose numbers up to 1,200 [100 in this unit] in more than one way as a sum of so many thousands, hundreds, tens, and ones
      • 2.2E locate the position of a given whole number on an open number line
      • 2.2F name the whole number that corresponds to a specific point on a number line
      • 2.4A recall basic facts to add and subtract within 20 with automaticity
      • 2.7B use an understanding of place value to determine the number that is 10 or 100 more or less than a given number up to 1,200 [100 in this unit]
      • 2.9C represent whole numbers as distances from any given location on a number line
  • Problem Solving
    • 2.4C solve one-step and multi-step word problems involving addition and subtraction within 1,000 [100 in this unit] using a variety of strategies based on place value, including algorithms
    • 2.4D generate and solve problem situations for a given mathematical number sentence involving addition and subtraction of whole numbers within 1,000 [100 in this unit].
  • Representing
    • 2.7C represent and solve addition and subtraction word problems where unknowns may be any one of the terms in the problem
Computational Fluency TEKS

Addition Fact Strategies

  • 2.4A recall basic facts to add and subtract within 20 with automaticity [Use Doubles and Make Ten strategies in this unit]

1st Grade Skip Counting

  • 1.5B skip count by twos, fives, and tens to determine the total number of objects up to 120 in a set; [Skip count by twos and tens in this unit starting at 0 and from other numbers]
Spiral Review TEKS

1st Grade Measurement Concepts (Length and Time)

  • 1.7D  Describe a length to the nearest whole unit using a number and a unit
    • 1.7A  Use [non-standard] measuring tools to measure the length of objects to reinforce the continuous nature of linear measurement
    • 1.7B  Illustrate that the length of an object is the number of same-size units of length that, when laid end-to-end with no gaps or overlaps, reach from one end of the object to the other
    • 1.7C  Measure the same object/distance with units of two different lengths and describe how and why the measurements differ
  • 1.7E  Tell time to the hour and half hour using analog and digital clocks