### TEKS

2.1 Mathematical process standards. The student uses mathematical processes to acquire and demonstrate mathematical understanding. The student is expected to:

• B. Use a problem-solving model that incorporates analyzing given information, formulating a plan or strategy, determining a solution, justifying the solution, and evaluating the problem-solving process and the reasonableness of the solution.
• C. 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.
• D. Communicate mathematical ideas, reasoning, and their implications using multiple representations, including symbols, diagrams, graphs, and language as appropriate.
• E. Create and use representations to organize, record, and communicate mathematical ideas.
• F. Analyze mathematical relationships to connect and communicate mathematical ideas.
• G. Display, explain, and justify mathematical ideas and arguments using precise mathematical language in written or oral communication.

2.4 Number and operations. The student applies mathematical process standards to develop and use strategies and methods for whole number computations in order to solve addition and subtraction problems with efficiency and accuracy. The student is expected to:

• A. Recall basic facts to add and subtract within 20 with automaticity.
• B. 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.

2.7 Algebraic reasoning. The student applies mathematical process standards to identify and apply number patterns within properties of numbers and operations in order to describe relationships. The student is expected to:

• C. Represent and solve addition and subtraction word problems where unknowns may be any one of the terms in the problem.

### Common Core

Operations & Algebraic Thinking: