Grade 3 Mathematics Module 3, Topic C, Overview

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Topic C anticipates the formal introduction of the associative property with a lesson on making use of structure to problem solve.  Students learn the conventional order for performing operations when parentheses are and are not present in an equation (3.OA.8).  With this knowledge in place, the associative property emerges in the next lessons as a strategy to multiply using units up to 8 (3.OA.5).  Units of 6 and 8 are particularly useful for presenting this Level 3 strategy.  Rewriting 6 as 2 × 3 or 8 as 2 × 4 makes shifts in grouping readily apparent (see example below), and also utilizes familiar factors 2, 3, and 4 as students learn the new material.  The following strategy may be used to solve a problem like 8 × 5:

8 × 5 = (4 × 2) × 5  

8 × 5 = 4 × (2 × 5)  

8 × 5 = 4 × 10

In the final lesson of Topic C, students relate division using units up to 8 with multiplication.  They understand division as both a quantity divided into equal groups and an unknown factor problem for which—given the large size of units—skip-counting to solve can be more efficient than dividing (3.OA.3, 3.OA.4, 3.OA.7).

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Common Core Learning Standards

CCLS State Standard
3.OA.3 Use multiplication and division within 100 to solve word problems in situations involving equal...
3.OA.4 Determine the unknown whole number in a multiplication or division equation relating three whole...
3.OA.5 Apply properties of operations as strategies to multiply and divide.2 Examples: If 6 × 4 = 24 is...

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