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# Solve problems involving the four operations, and identify and explain patterns in arithmetic

### Scaffolded Ideas

- The four operations are addition, subtraction, multiplication and division.
- Mental computation and estimation, including rounding, are strategies that can be used to “assess the reasonableness” of an answer to a two-step word problem.

### Questions to focus instruction:

- What is “estimating” and when is it used?
- What does it mean to “round”?
- What is an “arithmetic pattern”? What are some examples?

### Associated Standards:

3.OA.D.8 - Solve two-step word problems using the four operations. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding.
3.OA.D.9 - Identify arithmetic patterns (including patterns in the addition table or multiplication table), and explain them using properties of operations. For example, observe that 4 times a number is always even, and explain why 4 times a number can be decomposed into two equal addends.