Kindergarten Math - Study and Practice: Addition and Subtraction Up to 5

Completing Addition and Subtraction Sentences Up to 5

In some addition and subtraction problems, one of the numbers is missing. Students solve by figuring out what is added or taken away, what is left, and what was there to begin with. This builds understanding of how numbers work together in different positions of an equation.

Example Problems:

[] + 2 = 4 → Think: what number plus 2 equals 4? Answer: 2
5 − [] = 3 → What number must be taken away from 5 to get 3? Answer: 2
1 + 3 = [] → Start at 1 and count up 3. Answer: 4

Teacher Tip

Encourage students to read each number sentence out loud using “plus,” “minus,” and “equals” to strengthen math vocabulary and comprehension.

Using Objects or Visual Models

Using real or visual objects, such as counters, blocks, or toy animals, helps students test different possibilities until they find the missing number. This concrete approach makes abstract math more meaningful and easier to understand.

Hands-On Examples:

[] − 1 = 2 → Try 3 counters: 3 − 1 = 2, so the missing number is 3.
2 + [] = 5 → Add 3 counters to 2 counters: total is 5, so the missing number is 3.
4 − 0 = [] → Removing nothing leaves 4, so the missing number is 4.

Helpful Strategy

Have students physically add or remove counters, then count the total. This reinforces that addition means “putting together” and subtraction means “taking away.”

Counting Strategies

When the first number is known, counting forward helps find an addition answer, while counting backward helps find a subtraction answer. If the first number is missing, students can count up from the result to the total for addition, or from the result to the starting number for subtraction.

Counting Examples:

3 + [] = 5 → Count forward from 3: 4, 5. That’s 2 steps, so the missing number is 2.
[] − 2 = 1 → Start at 1 and count forward 2: 2, 3. The missing number is 3.
5 − 3 = [] → Count back from 5: 4, 3, 2. Answer is 2.

Instructional Tip

Model counting both forward and backward using a number line or fingers to give students a visual and tactile way to track their steps.

Writing Number Sentences in Different Forms

Number sentences can have the missing number in any position: the first number, the second number, or the answer. Understanding this flexibility helps students become stronger problem solvers.

Examples:

[] + 4 = 5 → Missing number is 1.
2 − [] = 0 → Missing number is 2.
3 + 1 = [] → Missing number is 4.

Math Language

Have students restate the problem in words after solving, such as “One plus four equals five,” to connect spoken and written math forms.

Checking the Answer

Students should check their answer by placing the missing number back into the sentence to confirm it is true. This builds accuracy and self-correction habits.

Checking Examples:

[] + 2 = 4 → Try 2: 2 + 2 = 4 ✓
5 − [] = 3 → Try 2: 5 − 2 = 3 ✓
1 + 3 = [] → Try 4: 1 + 3 = 4 ✓

Helpful Tip

Teach students that checking is like testing a puzzle piece to see if it fits — it should complete the picture perfectly.

Making Real-Life Connections

Linking addition and subtraction to everyday activities helps children understand why these skills matter. Activities like sharing snacks, putting away toys, or adding crayons to a box can become simple math problems.

Real-Life Examples:

You have 2 cookies and get 3 more. How many in all? 2 + 3 = 5.
You have 4 toy cars and give away 1. How many left? 4 − 1 = 3.
You see 5 birds, and 5 fly away. How many remain? 5 − 5 = 0.

Engagement Tip

Use familiar and relatable situations to help students visualize and connect with the math they are learning.

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