Multiplication and Division, Part 1

Lesson 3

Objective

Identify and create situations involving unknown group size and find group size in situations.

Common Core Standards

Core Standards

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  • 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

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

Tips for Teachers

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  • The following material is needed for today's lesson: Counters

Remote Learning Guidance

If you need to adapt or shorten this lesson for remote learning, we suggest prioritizing Anchor Task 2 (benefits from worked example) and Anchor Task 3 (can be done independently). Find more guidance on adapting our math curriculum for remote learning here.

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Anchor Tasks

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Problem 1

Split 18 counters equally into two groups. 

a. How many counters do you have in each group? 

b. Write a multiplication equation to represent this situation.

Guiding Questions

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Problem 2

a.  The pet store owner has 30 dog treats and feeds the same amount of treats to each of the dogs below.

i. Write a multiplication equation to represent this problem. 

ii. How many treats does he feed to each dog?

b. Mr. Peddie is arranging 20 chairs into 4 rows in the gymnasium for the spring performance.

i. Write a multiplication equation to represent this problem.

ii. How many chairs does he put in each row?

Guiding Questions

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Problem 3

Draw a picture or write a story to represent this multiplication situation. Then find the solution. 

$$5\times $$ ____ $$=10$$

Guiding Questions

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Problem Set & Homework

Discussion of Problem Set

  • What was similar about #8 and #9? What was different? 
  • Why was the unknown factor always the second one in our multiplication equations today? 
  • How did your visual models in #11 and #12 help you to determine the unknown factor? Did anyone use a different strategy to solve?

Target Task

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Problem 1

There are 20 glue sticks for the class. The teacher splits them into 4 equal groups. Draw the number of glue sticks in each group. 

References

EngageNY Mathematics Grade 3 Mathematics > Module 1 > Topic B > Lesson 4Exit Ticket, Question #1

Grade 3 Mathematics > Module 1 > Topic B > Lesson 4 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 The Match Foundation, Inc.

Problem 2

Which expression can be used to find the number of glue sticks in each group?

A.    $$4 \times 20 =$$ ____

B.    $$20 – 4 =$$ ____

C.    $$4\times$$ ____ $$=20$$

D.    $$4+$$ ____ $$=20$$

References

EngageNY Mathematics Grade 3 Mathematics > Module 1 > Topic B > Lesson 4Exit Ticket, Question #1

Grade 3 Mathematics > Module 1 > Topic B > Lesson 4 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 The Match Foundation, Inc.

Problem 3

Draw a picture to show $$3\times$$ ____ $$=15$$. Then, fill in the blank to make a true multiplication equation. 

$$3\times$$ ____ $$=15$$

References

EngageNY Mathematics Grade 3 Mathematics > Module 1 > Topic B > Lesson 4Exit Ticket, Question #2

Grade 3 Mathematics > Module 1 > Topic B > Lesson 4 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 The Match Foundation, Inc.

Mastery Response

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