Subtraction Strategies and Concepts

This video tutorial teaches subtraction within 100 using open number lines and friendly numbers. It begins with an introduction to the concept of friendly numbers, followed by a review of number building and skip counting. The tutorial then explains how to use open number lines for subtraction, providing examples and practice problems to reinforce the concepts. Key points include the non-commutative nature of subtraction and the decomposition of numbers to simplify subtraction.

What is the first step in solving 57 minus 9 using friendly numbers?

• Subtract 9 directly from 57

• Add 9 to 57

• Subtract 7 to reach a friendly number

• Subtract 2 to reach a friendly number

Which of the following is NOT a way to decompose the number 9?

• 4 + 5

• 2 + 7

• 1 + 8

• 5 + 5

What is the result of skip counting backwards by 10 from 100?

• 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 0

• 100, 90, 70, 50, 30, 10

• 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50

• 100, 80, 60, 40, 20, 0

Why is subtraction not considered commutative?

• Because the order of numbers affects the result

• Because subtraction results in the same number regardless of order

• Because subtraction can be done in any order

• Because subtraction is the same as addition

What is the result of 57 minus 9 using an open number line?

• 48

• 50

• 49

• 47

How do you decompose 8 to subtract it from 72 using a number line?

• Into 4 and 4

• Into 2 and 6

• Into 3 and 5

• Into 1 and 7

What is the final result when subtracting 8 from 72 using an open number line?

• 64

• 66

• 62

• 68

What is the first step in subtracting 9 from 96 using a number line?

• Subtract 9 directly

• Hop down to the nearest ten

• Add 9 to 96

• Subtract 3 first

What is the result of subtracting 9 from 96 using an open number line?

• 87

• 86

• 88

• 89

What is the purpose of using friendly numbers in subtraction?

• To simplify the subtraction process

• To multiply numbers more easily

• To make subtraction more difficult

• To add numbers more easily