MA.5.A.2.3Archived Standard

Make reasonable estimates of fraction and decimal sums and differences, and use techniques for rounding.


Remarks:  Use a variety of strategies for estimating sums and differences of fractions and decimals including benchmark fractions and decimals, and rounding techniques.


Example:  Students know that 7/8 + 11/12 is close to 2, because 7/8 and 11/12 are each close to 1.


Example:  Use appropriate benchmarks to estimate the difference between 1.801 and 1.239, be sure to show all work.

Possible Answers:  1.75 – 1.25 = 0.5  OR  1 ¾ - 1 ¼ = ½ 


Example:  Use an appropriate strategy to estimate the total cost for a shirt that costs $5.89 and a pair of shorts that costs $6.34, justify your answer.

Possible Answers:  If I round each of the cost to the nearest tenth, then $5.90 + $6.30 = $12.20.  OR  Since one costs slightly less than $6 and the other costs slightly more than $6, I would estimate the total cost to be 2 × $6 = $12.

General Information
Subject Area: X-Mathematics (former standards - 2008)
Grade: 5
Body of Knowledge: Algebra
Idea: Level 2: Basic Application of Skills & Concepts
Big Idea: BIG IDEA 2 - Develop an understanding of and fluency with addition and subtraction of fractions and decimals.
Date Adopted or Revised: 09/07
Date of Last Rating: 06/07
Status: State Board Approved - Archived
Assessed: Yes

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Lesson Plan

Adding and Subtracting Mixed Numbers with Unlike Denominators:

This lesson helps fifth graders combine their understanding of adding and subtracting fractions with unlike denominators, finding equivalent fractions, and adding and subtracting mixed numbers with like denominators to move on to adding and subtracting mixed numbers with unlike denominators.

Type: Lesson Plan

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