LAC 28:CXLII.505. Algebraic Reasoning

A. Represent and solve problems involving addition and subtraction. 1. Use addition and subtraction within 20 to solve real-world mathematical tasks involving situations of adding to, taking from, putting together, taking apart, and comparing with unknowns in all positions. a. Represent these situations using models and equations, elevating the concrete-representational-abstract instructional framework. 2. Solve real-world mathematical tasks that call for addition of three whole numbers whose sum is less than or equal to 20. a. Represent these situations using models and equations, elevating the concrete-representational-abstract instructional framework. B. Understand and apply properties of operations and the relationship between addition and subtraction. 1. Apply properties of operations to add and subtract. 2. Understand subtraction as an unknown-addend problem. C. Work with addition and subtraction equations. 1. Interpret the meaning of the equal sign. a. Understand that the equal sign represents a relationship where expressions on each side of the equal sign represent the same value(s). b. Determine if equations involving addition and subtraction are true or false. 2. Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. D. Compare numbers. 1. Compare two, two-digit numbers based on values of the tens and ones digits, recording the results of comparisons with comparative language or the symbols >, =, < and the words greater than, equal to, and less than. E. Use place value understanding and properties of operations to add and subtract. 1. Add up to 99, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10. a. Use concrete models or drawings and strategies based on place value, properties of operations, and/or the part:whole relationship between addition and subtraction; relate the strategy to a number sentence. b. Understand that in adding two-digit numbers, add tens and tens, ones and ones; and sometimes it is necessary to compose a ten. c. Justify the reasoning of methods for addition used with an oral and/or written explanation. 2. Subtract two digit numbers, limited to multiples of 10 using concrete models or drawings and strategies based on place value, properties of operations, and/or the part:whole relationship between addition and subtraction. a. Justify the reasoning used when choosing the model or strategy to compute with an oral and/or written explanation.