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 1
Quarter 2
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 = ?.
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 = ?.

Increasing Rigor

  • I am thinking of two numbers on the number line that have a difference of 5. What could the two numbers be? How do you know?
  • If the sum of two numbers is 13, what could the two addends be? How do you know?
  • Use the digits 3, 4, 5, 6 & 7 to make the following equations true. Each digit may be used only once. (_ + 6 = 12, 5 - _ = 2, 4 = _ - 3, 6 = 2 + _13 - ___ = 8)
  • A ribbon is 14 inches long. Jan used some ribbon to wrap a gift. How much ribbon could be left?. How many inches of ribbon did Jan use? Write a number sentence show how you solved the problem.

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. Essential vocabulary for this standard includes: addition, add, subtraction, subtract, and equation (online dictionary, HCPSS Vocabulary Cards).

The Illustrative Mathematics Project tasks below demonstrate expectation for this standard.

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
Balance
Missing
Full Lessons
Block Pounds
Try For Five
Modeling Subtraction
If you Give a Mouse a Cookie
Pick a Card, Any Card

Illustrative Mathematics Project
Finding Missing Numbers

Printable Tools
Fact Family CardsMissing First Addend ModelsMissing Second Addend Models



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.