Adding Numbers within 100 Using an Open Number Line

The video tutorial teaches how to add numbers within 100 using an open number line. It begins with an introduction to the concept, followed by a review of making 10 and skip counting by 10s. The tutorial then demonstrates how to use an open number line for addition, addressing common misunderstandings such as place value errors. Finally, it provides examples of adding numbers using this method, emphasizing the importance of decomposing numbers to reach friendly numbers.

What is a friendly number, and why is it useful in addition?

• A number that is a multiple of 10, making addition simpler

• A number that is always even

• A number that is less than 5

• A number that is easy to subtract

How can you use an open number line to add 14 and 3?

• Start at 3 and hop up 14 spaces to reach 17

• Start at 3 and hop up 10 spaces to reach 13

• Start at 14 and hop up 3 spaces to reach 17

• Start at 14 and hop up 10 spaces to reach 24

When adding 46 and 8 using an open number line, what is the first step?

• Hop directly to 54

• Hop to 60 and subtract 6

• Decompose 8 into 4 and 4, then hop to 50

• Add 8 to 46 without using the number line

What is a common mistake when adding numbers like 4 and 60?

• Mixing up the place values and thinking the answer is 100

• Adding the tens and ones separately

• Subtracting instead of adding

• Ignoring the number line

How do you add 68 and 7 using an open number line?

• Hop directly to 75

• Decompose 7 into 2 and 5, hop to 70, then add 5

• Add 7 to 68 without using the number line

• Hop to 80 and subtract 5