Missing Number Adventures: Cracking Equations!

Math Grades 1st Grade 15:26 Video
Print Lesson Plan Watch Video

Lesson Description

Learn how to find missing numbers in addition and subtraction problems using number families! We'll use fun strategies to solve equations and become math detectives.

Video Resource

Equations: Addition and Subtraction | 1st Grade | Math | Kids Academy

Kids Academy

Duration: 15:26
Watch on YouTube

Key Concepts

  • Equations
  • Addition
  • Subtraction
  • Missing Numbers
  • Number Families (Associative Property)

Learning Objectives

  • Students will be able to identify the missing number in an addition or subtraction equation.
  • Students will be able to use the 'number family' strategy (based on associative property) to solve for the missing number.
  • Students will be able to check their answers by plugging the solution back into the original equation.

Educator Instructions

  • Introduction (5 mins)
    Start by asking students what they already know about addition and subtraction. Introduce the idea of 'missing numbers' in equations, like a puzzle to solve. Briefly explain that you are going to be Math Detectives!
  • Video Viewing (10 mins)
    Play the Kids Academy video 'Equations: Addition and Subtraction'. Encourage students to pay attention to the 'number family' strategy and how the narrator solves the problems.
  • Number Family Explanation (10 mins)
    Explain the concept of a 'number family' (associative property) using simple examples like 2, 3, and 5. Draw the 'house' to visually represent how these numbers relate to each other in both addition and subtraction. Emphasize that the biggest number is on top for organization.
  • Solving Equations Together (15 mins)
    Work through 2-3 example problems from the video transcript together on the board. Model how to set up the 'number family' house, rearrange the equation if needed, and solve for the missing number. Encourage students to participate and explain their thinking.
  • Practice Problems (15 mins)
    Give students 3-4 similar equation problems to solve independently or in pairs. Circulate to provide support and guidance as needed. Encourage them to check their answers using the 'number family' house.
  • Wrap-Up (5 mins)
    Review the key concepts learned in the lesson. Ask students to share their favorite strategy for solving missing number problems.

Interactive Exercises

  • Number Family Sort
    Provide index cards with numbers written on them. Have students work in groups to create 'number families' by finding three cards that relate to each other through addition and subtraction.
  • Equation Building
    Provide students with number tiles and operation signs (+, -, =). Call out a missing number equation, and have students work together to build the equation and solve for the missing number.

Discussion Questions

  • What happens when we add the same numbers in a different order? (e.g., 2+3 vs. 3+2)
  • How can knowing our 'number families' help us solve subtraction problems?
  • Why is it important to check our answers after we solve an equation?

Skills Developed

  • Problem-solving
  • Critical thinking
  • Number sense
  • Equation solving
  • Application of associative property

Multiple Choice Questions

Question 1:

Which number is missing? 2 + ___ = 5

Correct Answer: 3

Question 2:

Which number is missing? ___ - 1 = 4

Correct Answer: 5

Question 3:

Which number is missing? 6 = 3 + ___

Correct Answer: 3

Question 4:

If 2 + 4 = 6, then what is 6 - 4?

Correct Answer: 2

Question 5:

If 5 - 2 = 3, then what is 2 + 3?

Correct Answer: 5

Question 6:

Which number is missing? 10 - ___ = 5

Correct Answer: 5

Question 7:

Which number is missing? ___ + 2 = 8

Correct Answer: 6

Question 8:

Which number is missing? 7 - ___ = 3

Correct Answer: 4

Question 9:

Which number is missing? 4 = ___ - 1

Correct Answer: 5

Question 10:

Which number is missing? 9 = 6 + ___

Correct Answer: 3

Fill in the Blank Questions

Question 1:

4 + ___ = 7

Correct Answer: 3

Question 2:

___ - 2 = 5

Correct Answer: 7

Question 3:

6 = ___ + 1

Correct Answer: 5

Question 4:

If 3 + 2 = 5, then 5 - 2 = ___

Correct Answer: 3

Question 5:

If 8 - 3 = 5, then 3 + 5 = ___

Correct Answer: 8

Question 6:

9 - ___ = 4

Correct Answer: 5

Question 7:

___ + 1 = 6

Correct Answer: 5

Question 8:

5 - ___ = 1

Correct Answer: 4

Question 9:

2 = ___ - 3

Correct Answer: 5

Question 10:

7 = 4 + ___

Correct Answer: 3

Educational Standards

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.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.A.1:Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

Teaching Materials

Download ready-to-use materials for this lesson:

Student Worksheet Classroom Slides Assessment Quiz Export to Google Docs
Add to Google Classroom

User Actions

Sign in to save this lesson plan to your favorites.

Sign In

Share This Lesson

Related Lesson Plans