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 marshmallow problem and introduces the concept of fact families, showing how to write related equations. The tutorial covers solving for unknown addends and sums, highlights common mistakes, and applies these concepts to solve the initial problem. The lesson concludes with a summary of the key points.

What is the largest number in a fact-family triangle?

• The subtrahend

• The sum

• The difference

• The smallest addend

If you have the equation 9 plus blank equals 22, what is the missing number?

• 17

• 11

• 15

• 13

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

• Using addition instead of subtraction

• Using multiplication instead of division

• Using subtraction instead of addition

• Using division instead of multiplication

In the marshmallow problem, how many marshmallows were eaten?

• 7

• 26

• 33

• 19

How many marshmallows were originally in the bag?

• 44

• 26

• 33

• 7