Adding 9: A Number Adventure!

Math Grades 1st Grade 8:56 Video
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Lesson Description

Learn how to add 9 to any number by understanding the relationship between adding 9 and adding 10. We'll use fun tools like ten-frames and number charts!

Video Resource

Grade 1: Saxon Math Lesson #108 Adding 9 To A Number - Addition Facts

The Eagle's Nest - Our Online Classroom

Duration: 8:56
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Key Concepts

  • Adding 10 to a number
  • Adding 9 to a number
  • Relationship between adding 9 and adding 10
  • Using manipulatives to add

Learning Objectives

  • Students will be able to add 10 to a number within 20.
  • Students will be able to add 9 to a number within 20.
  • Students will understand that adding 9 is the same as adding 10 and subtracting 1.
  • Students will be able to use manipulatives (like Legos or counters) to visualize addition.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing adding 10 to numbers. Use a ten-frame to visualize adding 10, similar to the video's demonstration with Legos. Ask: What happens when we add 10 to the number 4? What about 7?
  • Exploring Adding 9 (10 mins)
    Introduce the concept of adding 9. Explain that 9 is one less than 10. Use a nine-frame (or a ten-frame with one space covered) to visually represent adding 9. Do a sample problem from the video, like 6+9.
  • Comparing Adding 9 and 10 (10 mins)
    Work through several examples, comparing the results of adding 9 and 10 to the same number. For instance: 5 + 10 = 15, 5 + 9 = 14. Emphasize that the answer when adding 9 is always one less than when adding 10.
  • Practice with Number Chart (10 mins)
    Use a 100s chart to practice adding 9. Have students start on a number and then count 9 spaces forward. Relate this to moving down one row (adding 10) and back one space (subtracting 1).
  • Wrap-up (5 mins)
    Review the main concept: Adding 9 is like adding 10 and then taking away 1. Encourage students to use their fingers, counters, or number charts to help them solve addition problems with 9.

Interactive Exercises

  • Ten-Frame Fun
    Provide each student with a ten-frame and counters (or small objects like Legos). Call out addition problems (e.g., 7 + 9). Have students fill the ten-frame to represent the first number and then add counters for the '9,' relating this to filling a full ten-frame and having some left over.
  • Number Chart Challenge
    Give students a 100s chart and have them practice adding 9 to different numbers. Encourage them to notice the pattern on the chart.

Discussion Questions

  • What happens when you add 10 to a number?
  • How is adding 9 different from adding 10?
  • Can you think of a time when knowing how to add 9 quickly would be helpful?

Skills Developed

  • Addition
  • Number Sense
  • Problem-Solving
  • Visual Representation

Multiple Choice Questions

Question 1:

What is 5 + 10?

Correct Answer: 15

Question 2:

What is 5 + 9?

Correct Answer: 14

Question 3:

9 is one less than what number?

Correct Answer: 10

Question 4:

If you add 10 to a number, and then take 1 away, it's the same as adding:

Correct Answer: 9

Question 5:

What is 2 + 10?

Correct Answer: 12

Question 6:

What is 2 + 9?

Correct Answer: 11

Question 7:

Which tool can help you add?

Correct Answer: Ten-Frame

Question 8:

If 6 + 10 = 16, what is 6 + 9?

Correct Answer: 15

Question 9:

What is 10 + 10?

Correct Answer: 20

Question 10:

What is 10 + 9?

Correct Answer: 19

Fill in the Blank Questions

Question 1:

Adding 9 is like adding 10 and taking away ____.

Correct Answer: 1

Question 2:

9 + 10 = ____

Correct Answer: 19

Question 3:

9 + 9 = ____

Correct Answer: 18

Question 4:

When you add 9 to a number, the answer is always ____ less than when you add 10.

Correct Answer: 1

Question 5:

We can use a ________ to help us add.

Correct Answer: ten-frame

Question 6:

7 + 10 = ____

Correct Answer: 17

Question 7:

7 + 9 = ____

Correct Answer: 16

Question 8:

____ + 10 = 18

Correct Answer: 8

Question 9:

____ + 9 = 17

Correct Answer: 8

Question 10:

If you have 10 cookies and eat 1, you have ____ cookies left.

Correct Answer: 9

Educational Standards

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). CCSS.Math.Content.1.NBT.C.5:Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. 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.

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