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• Math: Developing 3-Digit Addition and Subtraction Strategies

# Math: Developing 3-Digit Addition and Subtraction Strategies

### Suggested Time Frame: 20 Instructional Days

##### Focus TEKS

Adding and Subtracting with 3-Digit Numbers

• Computation
• 2.4B add up to four two-digit numbers and subtract two-digit numbers using mental strategies and algorithms based on knowledge of place value and properties of operations
• Problem Solving
• 2.4C solve one-step and multi-step word problems involving addition and subtraction within 1,000 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.
• Representing
• 2.7C represent and solve addition and subtraction word problems where unknowns may be any one of the terms in the problem
##### Numeracy TEKS

Counting Patterns (Suggested: 4 days)

• 2.5A determine the value of a collection of coins up to one dollar [pennies, nickels, dimes, and quarters]
• 2.5B use the cent symbol, dollar sign, and the decimal point to name the value of a collection of coins
• RRISD 2.7B Skip count forward and backward by ten and one hundred from any given number up to 1,000

Building Fluency with Addition and Subtraction within 20 (Suggested: 4 days)

• 2.4A recall basic facts to add and subtract within 20 with automaticity

Developing Strategies for Adding and Subtracting 2-Digit Numbers (Suggested: 10 days)

• 2.4B add up to four two-digit numbers and subtract two-digit numbers using mental strategies and algorithms based on knowledge of place value and properties of operations
##### Spiral Review TEKS

Revisiting Joining and Separating Equal Groups (Suggested: 18 days)

• 2.6 The student applies mathematical process standards to connect repeated addition and subtraction to multiplication and division situations that involve equal groupings and shares.
• 2.6A model, create, and describe contextual multiplication situations in which equivalent sets of concrete objects are joined
• 2.6B model, create, and describe contextual division situations in which a set of concrete objects is separated into equivalent sets
• 2.7A determine whether a number up to 40 is even or odd using pairings of objects to represent the number

Counting Quantities (Suggested: 2 days, using both numeracy and spiral review time)

• RRISD 2.1 organize and count a collection of objects and create a recording of how the objects were counted
• 2.1C  select tools, including real objects, manipulatives, paper and pencil, and technology as appropriate, and techniques, including mental math, estimation, and number sense as appropriate, to solve problems;
• 2.1E  create and use representations to organize, record, and communicate mathematical ideas;
• Counting Coins (Make this the focus on 1 day of Counting Collections)

• 2.5A determine the value of a collection of coins up to one dollar
• 2.5B use the cent symbol, dollar sign, and the decimal point to name the value of a collection of coins

Telling Time (Ongoing)

• 2.9G read and write time to the nearest one-minute increment using analog and digital clocks and distinguish between a.m. and p.m.