Solving Unknowns with Addition and Subtraction Fact Families

The video tutorial explains how to solve for unknown amounts using addition and subtraction fact families. It begins with a problem involving marshmallows and demonstrates how to use fact families to find unknown values. The tutorial covers common mistakes and provides strategies for solving equations. It concludes by applying these concepts to solve the original marshmallow problem.

How many marshmallows did Laura and her friends eat?

• 17

• 26

• 7

• 33

What is the purpose of this lesson?

• To solve for unknown amounts using addition and subtraction fact families

• To learn division

• To learn multiplication

• To solve geometry problems

Which of the following is a correct fact family for the add-ins 17 and 8?

• 17 + 8 = 25, 8 + 17 = 25, 25 - 8 = 17, 25 - 17 = 9

• 17 + 8 = 25, 8 + 17 = 25, 25 - 8 = 17, 25 - 17 = 8

• 17 + 8 = 25, 8 + 17 = 25, 25 - 17 = 8, 25 - 8 = 9

• 17 + 8 = 25, 8 + 17 = 25, 25 - 8 = 9, 25 - 17 = 7

What is the missing add-in in the equation 9 + ___ = 22?

• 13

• 15

• 12

• 14

What is a common mistake when solving for an unknown in subtraction?

• Ignoring the problem

• Adding the numbers directly

• Using the opposite operation

• Using the same operation

If you have the equation 30 - ___ = 12, what should you do to find the unknown?

• Divide 30 by 12

• Add 30 and 12

• Subtract 12 from 30

• Multiply 30 and 12

What is the unknown sum in the equation ___ - 6 = 38?

• 32

• 44

• 42

• 40

What is the correct way to solve for an unknown when the sum is missing?

• Use the same operation

• Use the opposite operation

• Add the known values

• Ignore the problem

How many marshmallows were in the bag initially?

• 26

• 7

• 17

• 33

Which of the following is a related addition fact for the equation ___ - 26 = 7?

• 26 + 7 = 33

• 26 + 7 = 32

• 26 + 7 = 30

• 26 + 7 = 31