# 2. Playing Fill Three: Multiplying unit fractions by whole numbers (FP)

teaches Common Core State Standards CCSS.Math.Content.4.NF.B.4a http://corestandards.org/Math/Content/4/NF/B/4/a
teaches Common Core State Standards CCSS.Math.Practice.MP1 http://corestandards.org/Math/Practice/MP1
teaches Common Core State Standards CCSS.Math.Practice.MP6 http://corestandards.org/Math/Practice/MP6
teaches Common Core State Standards CCSS.Math.Practice.MP8 http://corestandards.org/Math/Practice/MP8

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Lesson objective: Multiply a unit fraction by a whole number.

This lesson helps to build fluency with multiplying a unit fraction by a whole number. Number lines are used here because they support the understanding that fractions are numbers and can be operated on in the same ways as whole numbers can be operated on. They also support the connection between repeated addition and multiplication. This work develops students' understanding that a fraction a/b is a multiple of 1/b.

Students engage in Mathematical Practice 8 (look for and express regularity in repeated reasoning) as they notice that instead of repeatedly adding the same unit fraction, they can multiply the unit fraction. Modeling both the repeated addition and the multiplication on a number line helps students generate and understand how the algorithm [a x 1/b = a/b] works.

Key vocabulary:

• denominator
• multiple
• non-unit fraction
• unit fraction

Special materials needed:

• colored writing utensils such as colored pencils or markers
• fraction game board (see additional materials)
• paper clip
• game spinners (see additional materials)
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