Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ? – 3, 6 + 6 = ?.


Quarter 3
Quarter 4
Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ? – 3, 6 + 6 = ?.
Determine the unknown whole number in an addition or subtraction equation relating to three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = ? – 3, 6 + 6 = ?.

Enduring Understanding

Mathematical operations are used in solving problems in which a new value is produced from one or more values.
Algebraic thinking involves choosing, combining, and applying effective strategies for answering quantitative questions.

Essential Questions

In what ways can operations affect numbers?
How can different strategies be helpful when solving a problem?

Vocabulary (online dictionary, HCPSS Vocabulary Cards)

Addition, add, subtraction, subtract, equation

About the Math

This standard is critical in developing students' problem solving skills, algebraic foundations, and understanding of addition and subtraction. There are two types of part-part-whole problems. In one type, the sizes of both parts are given and the student has to find the whole. Or students are given the size of one part and the size of the whole, and they need to find the size of the missing part. This concept is an extension of decomposing of numbers and students will use their understanding of decomposition of numbers when finding the missing part. Students may need to use counters to see how a number can be broken up into different parts before moving to the more abstract representation.

Illustrative Mathematics Project: Finding Missing Numbers

Rich Tasks for Multiple Means of Engagement, Expression, and Representation (UDL)

I Wish I Had (Van de Walle, K-3, p 51). Hold out a bar of connecting cubes, a ten-frame or dot plate showing 6 or less. Say, "I have this many, but I wish I had six." The children respond with the part that is needed to make six. Counting on can be used to check. The game can focus on a single whole ( like six) or the "I Wish I Had" number can change each time.

Other Instructional Resources:
Van de Walle, K-3 Activity 2.19 Missing-Part Cards, page 50 MissingPartActivities.png
Van de Walle, K-3 Activity 4.14 Missing Number Cards page 110

Rich Problem:
Aaron started with the number 10 on his calculator and ended with 20 without clearing the calculator display. Using a calculator, investigate and record the ways that Aaron might have used to get from 10 to 20.

Insert each of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 in the right spot. Each digit may only be used once. (Small, Good Questions, Great Ways to Differentiate Mathematics Instruction, p 43).
9 + _ = 1_
_ + 4 = 1 _
1 _ - 8 = 4
_ + _ = _ _
_ + 2 + 7

Journal Prompt:

Josie had to find a number to go in the blank for this problem:
6 + __ = 14
Find the missing number. Describe how you found the answer. Or draw a picture that shows how you found the answer.
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Print Resources

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Read It! Draw It! Solve It! Grade 1
(140, 158, 160, 162)
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Math Intervention: Building Number Power K-2
(111-121)
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Groundworks Algebraic Thinking Grade 1
(64-87)





Web Resources:

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Games and Centers
Lessons
Student Resources
Video Segments
Printable Game
Find the Missing Number

Online Games
Stop the Clock
Addition +
Missing Addend
Balance
Full Lessons
Block Pounds
Try For Five
Modeling Subtraction

Lesson SeedsTeaching Fact Families

Illustrative Mathematics Project
Finding Missing Numbers
Printable Tools
Fact Family CardsFunction Table TemplateMagic Pot Workmat

The Number Crew: After LIfeboat Practice






Connecting Children's Literature:

Click on the books for additional activities.
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Two Of Everything
By: Lily Toy Hong

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Safari Park
By: Stuart J. Murphy

Questions/Comments:

Contact John SanGiovanni at jsangiovanni@hcpss.org.


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Howard County Public Schools Office of Elementary Mathematics Curricular Projects has licensed this product under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.