Multiplication and Division, Part 1

Lesson 4

Math

Unit 2

3rd Grade

Lesson 4 of 21

Objective


Identify and create situations involving an unknown number of groups and find the number of groups in situations.

Common Core Standards


Core Standards

  • 3.OA.A.1 — Interpret products of whole numbers, e.g., interpret 5 × 7 as the total number of objects in 5 groups of 7 objects each. For example, describe a context in which a total number of objects can be expressed as 5 × 7.
  • 3.OA.A.2 — Interpret whole-number quotients of whole numbers, e.g., interpret 56 ÷ 8 as the number of objects in each share when 56 objects are partitioned equally into 8 shares, or as a number of shares when 56 objects are partitioned into equal shares of 8 objects each. For example, describe a context in which a number of shares or a number of groups can be expressed as 56 ÷ 8.
  • 3.OA.A.3 — Use multiplication and division within 100 to solve word problems in situations involving equal groups, arrays, and measurement quantities, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.

Criteria for Success


  1. Represent the number of groups and size of groups in a picture.
  2. Divide a number of objects into groups of a given size in order to find the number of groups. 
  3. Write a multiplication equation to represent a given situation or picture where the unknown is the number of groups, including the number of rows of an array (MP.2). 
  4. Draw a picture to represent a given multiplication equation where the unknown is the number of groups, including the number of rows of an array (MP.2).

Tips for Teachers


Lesson Materials

  • Counters (18 per student or small group) — Students could use a common classroom material, such as paperclips, instead.
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Anchor Tasks

25-30 minutes


Problem 1

a.   Split 18 counters equally into groups of two. 

i. Write a multiplication equation to represent this situation. 

ii. How many groups of counters do you have?

b.   How is this similar to Anchor Task #1 from Lesson 3? How is it different?

Guiding Questions

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Student Response

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Problem 2

a.   Casey bought the following stickers. She wants to put 5 stickers in each goodie bag for her birthday party. 

i. Write a multiplication equation to represent this problem. 

ii. How many goodie bags did Casey fill with stickers? 

b.    A grocery store puts 30 watermelons on display. They arrange them in rows of 10. 

i. Write a multiplication equation to represent this problem. 

ii. How many rows of watermelons are there?

Guiding Questions

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Student Response

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References

Problem 3

a.   Draw a picture or write a story to represent the following multiplication situation. 

___ $$\times \ 4 = 12$$

b.   Find the number that makes the equation true. Rewrite the equation with the solution.

Guiding Questions

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Student Response

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References

EngageNY Mathematics Grade 3 Mathematics > Module 1 > Topic B > Lesson 5Concept Development

Grade 3 Mathematics > Module 1 > Topic B > Lesson 5 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by Fishtank Learning, Inc.

Problem Set

15-20 minutes


Discussion of Problem Set

  • What was similar about #8 and #9? What was different? 
  • How did your visual models in #11 and #12 help you to determine the unknown factor? Did anyone use a different strategy to solve?
  • Did you "just know" the missing factor for any of the problems? Which one(s)?
  • How is your approach to drawing a model to represent a problem with an unknown number of groups different from your approach to drawing a model to represent a problem with an unknown group size? 
  • How are the multiplication equations we wrote today different from those we wrote yesterday? What explains this difference? 

Target Task

5-10 minutes


Problem 1

Split 18 apples into groups of 3 to find the number of groups. Then, fill in the blank to make a true multiplication equation. 

______ × 3 = 18

Student Response

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Problem 2

Silas washes 10 socks. He puts them in pairs of 2 and puts them in his dresser. How many pairs of socks did Silas make? Show or explain your work. 

Student Response

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Additional Practice


The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

Next

Relate multiplication and division and understand that division can represent situations of unknown group size or an unknown number of groups.

Lesson 5
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: The Meaning of Multiplication and Division

Topic B: Multiplication and Division by 2, 5, and 10

Topic C: Multiplication and Division by 3 and 4

Topic D: More Complex Multiplication and Division Problems

Topic E: Scaled Picture and Bar Graphs

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