Super Sleuths: Finding Missing Numbers!

Math Grades 1st Grade 3:52 Video
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Lesson Description

Let's become math detectives! In this lesson, we'll learn how to find missing numbers in addition problems by using subtraction. We'll use fact families to help us solve the puzzles!

Video Resource

Finding Unknown Addends and Missing Numbers - 1st Grade Math (1.OA.4)

Boddle Learning

Duration: 3:52
Watch on YouTube

Key Concepts

  • Fact Families
  • Inverse Relationship between Addition and Subtraction
  • Finding Missing Addends

Learning Objectives

  • Students will be able to identify the missing addend in an addition equation.
  • Students will be able to use subtraction to solve for the missing addend.
  • Students will understand the relationship between addition and subtraction within fact families.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they know about addition. Review what 'adding' means. Then, introduce the idea of a 'missing number' in an addition problem. Explain that today, they will become math detectives to find these missing numbers!
  • Video Viewing (5 mins)
    Play the Boddle Learning video: 'Finding Unknown Addends and Missing Numbers - 1st Grade Math (1.OA.4)'. Pause at key points to ask questions and ensure understanding.
  • Fact Family Review (5 mins)
    Review fact families. Use manipulatives (like blocks or counters) to show how three numbers can make two addition and two subtraction equations (e.g., 2, 3, and 5). Practice creating fact families together.
  • Guided Practice (10 mins)
    Write addition problems on the board with a missing addend (e.g., 4 + ? = 9). Guide students through the process of using subtraction to find the missing number (9 - 4 = 5). Do several examples together, encouraging student participation.
  • Independent Practice (10 mins)
    Provide students with a worksheet containing similar addition problems with missing addends. Allow them to work independently or in pairs to solve the problems. Circulate to provide support as needed.
  • Wrap-up (5 mins)
    Review the main points of the lesson. Ask students to share what they learned. Collect the worksheets and provide feedback.

Interactive Exercises

  • Number Bond Activity
    Use number bonds to visually represent the addition and subtraction relationships. Provide number bonds with a missing part and have students fill it in. For example: Circle with 7 at the top, one line pointing to a circle with 3, and another line pointing to an empty circle. Students fill in 4.
  • Manipulative Game
    Use counters or blocks. Start with a set number (e.g., 10). Hide some under a cup. Show the students how many are left (e.g., 6). Ask them to figure out how many are hidden under the cup (10 - 6 = 4).

Discussion Questions

  • What is a fact family?
  • How can subtraction help us solve addition problems with missing numbers?
  • Can you give me an example of a time you might need to find a missing number in real life?

Skills Developed

  • Addition
  • Subtraction
  • Problem-solving
  • Critical Thinking

Multiple Choice Questions

Question 1:

What number plus 2 makes 5?

Correct Answer: 3

Question 2:

If you have 8 cookies and eat 3, how many are left?

Correct Answer: 5

Question 3:

What does 'add' mean?

Correct Answer: Put together

Question 4:

In the number sentence 3 + ? = 7, what number is missing?

Correct Answer: 5

Question 5:

What is the opposite of addition?

Correct Answer: Subtraction

Question 6:

Which number makes this true? 5 + ? = 10

Correct Answer: 5

Question 7:

What is a fact family?

Correct Answer: A set of related addition and subtraction facts

Question 8:

If 9 - 4 = 5, then what is 4 + 5?

Correct Answer: 9

Question 9:

Which number goes in the blank? 1 + ___ = 6

Correct Answer: 5

Question 10:

If you know that 2 + 3 = 5, what is 5 - 2?

Correct Answer: 3

Fill in the Blank Questions

Question 1:

To find a missing number in addition, we can use ________.

Correct Answer: subtraction

Question 2:

A fact family is a group of numbers that are all ________.

Correct Answer: related

Question 3:

3 + ____ = 8. The missing number is ____.

Correct Answer: 5

Question 4:

If 6 + 2 = 8, then 8 - 2 = ____.

Correct Answer: 6

Question 5:

The opposite of adding is ________.

Correct Answer: subtracting

Question 6:

In the problem 4 + ? = 7, the missing number is ________.

Correct Answer: 3

Question 7:

We can use blocks or _________ to help us solve math problems.

Correct Answer: counters

Question 8:

If I have 10 apples and give away 4, I have _________ apples left.

Correct Answer: 6

Question 9:

9 + _____ = 11, The missing number is ______.

Correct Answer: 2

Question 10:

7 - ____ = 3, The missing number is ______.

Correct Answer: 4

Educational Standards

CCSS.Math.Content.1.OA.B.4:Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8. CCSS.Math.Content.1.OA.D.8:Determine the unknown whole number in an addition or subtraction equation relating 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 = _. CCSS.Math.Content.1.OA.C.6:Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).

Teaching Materials

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