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.

At Grade Level:
Students will translate word problems into number sentences and solve for any unknown quantity.




1This standard is limited to problems posed with whole numbers and having whole-number answers; students should know how to perform operations in the conventional order when there are no parentheses to specify a particular order.