Videos and songs to help Grade 1 kids learn how to determine the unknown whole number in an addition or subtraction equation relating three whole numbers.

For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _.

Common Core: 1.OA.8

### Learning Targets:

• I can determine the unknown value in an addition or subtraction equation when two out of three numbers in the equation are given.
Related Topics:

The Mystery of the Missing Addends
A fun story to help kids learn how to find missing addends using part part whole
Example:
3 + ? = 7 Solving addition and subtraction fact families when all three numbers are given and when there is a missing number Missing addends
Examples:
4 + ? = 7
? + 5 = 7 Missing Addend using Tens Frame
Using the tens frame to solve missing addend problems. Missing Addends: Finding a Missing Part
How to find a missing part using both addition or subtraction?
How to draw pictures to match a story problem?
Examples:
1. I got balloons at the fair. 4 of the balloons were green. The rest are red. How many are red?
2. My little sister got 3 pink balloons at the fair. Then she got some more yellow balloons. Now, she has 5 balloons in all. How many are yellow?

How to use subtraction to find missing addends?
Number bonds are pairs of friends
And all together they make ten.
They will stick together until the end.
They make ten! They make ten! Unknown Addend Story Problems
Examples:
1. There were 7 turkeys roaming the field. I saw 2 more turkeys roaming the field. How many turkeys did I see in all?

2. There were 7 turkeys roaming in the field. I saw some more turkeys join them in the field. Now I see 9 turkeys roaming in the field. How many turkeys joined the 7 turkeys?

3. 8 leaves fell from my tree. The second day, I saw some more leaves fall from my tree. Altogether, 13 leaves fell from my tree. How many leaves did I see fall the second day?

4. 4 minions were running around. 5 minions were eating bananas. How many minions were there in all?

5. 9 minions turned into evil purple minions. Then some more turned into evil purple minions later in the day. There were 11 evil purple minions in all. How many minions turned into evil purple minions later in the day?

Examples:
1. I have 5 pencils. Josh has 2 pencils.
How many more pencils does Josh need to have the same number of pencils as me?

An item costs \$7. I have \$3. How many more dollars do I need to but the item? Find the Missing Number (1.OA.8)

Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.