# 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.1

## Summary:

This skill is a capstone for the third grade student who has mastered basics facts and has a sophisticated knowledge base for the four mathematical operations. It is in this skill that they apply all their mastery into a variety of word problems that involve all four operations and solving for an unknown quantity. Students will use what they have learned to justify their answers as well.

## Understanding the Standard:

• The use of a variety of real-life, two-step word problems will enhance student learning and make math more applicable to their life.
• Students need a large vocabulary base in order to determine which operations are necessary for solution. Additionally, students should be familiar with the idea of order of operations.
• The use of pictures and diagrams is an important tool to aid students with problem-solving and is also useful for justifying a particular answer.

## Questions to Focus Learning:

• Can students move fluently between addition and subtraction as well as multiplication and division?
• Are students able to identify the key words in a word problem that will point to the particular operations that are necessary to solve a multi-step word problem?
• Are students able to translate a word problem into a numeric sentence and assign a variable to an unknown quantity?
• Can students assess the reasonableness of a solution using mental methods?
• Can students estimate a reasonable answer?

## Skills

Prior to: Students can fluently and with mastery, compute a variety of problems involving all four basic operations.