1.OA.8: Finding Missing Numbers

Visual Models

Balance Scale: Use a balance scale to show that both sides of an equation must be equal. Place weights on both sides to represent the equation.

Missing Number Boxes: Draw boxes to represent the unknown number in equations like 5 + □ = 12 or □ - 3 = 4.

Number Bond Models: Use number bonds to show how parts combine to make a whole, helping visualize the missing part in equations.

Everyday Activities

Hidden Number Hunt: Place sticky notes with numbers 1-10 around the house. Give your child equations with missing numbers (7 + ? = 10) and have them find the sticky note with the correct answer.

Equation Puzzles: Cut index cards into puzzle pieces. Write equations with missing numbers on one side and the complete equation on the other.

Balance Scale Challenges: Make a simple balance scale with a hanger and cups. Use small objects to represent numbers and create equations with missing values.

Missing Number Stories: Create simple stories with missing information: "I had some cookies. I ate 3 and now I have 5. How many did I start with?"

Strategies When Your Child Struggles

Think Addition for Subtraction: If your child struggles with 15 - ? = 8, reframe it as "8 plus what equals 15?"

Use Concrete Objects: For 7 + ? = 12, show 7 objects, then ask "How many more do we need to make 12?"

Cover and Reveal: Write the full equation (like 6 + 4 = 10), then cover one number with a sticky note.

Draw the Problem: For ? - 3 = 5, draw 5 circles, then explain that we started with more and took away 3.

5-Minute Practice Activities

Missing Number Cards: Create cards with simple equations missing one number. Have your child solve 5-10 problems.

Equation Race: Write 3 equations with missing numbers. Time your child solving them (aim for under 2 minutes).

Story Problems: Create quick word problems: "I have 8 stickers. I give some away and have 3 left. How many did I give away?"

Number Line Jumps: Use a number line to show missing addends: "Start at 4, jump to 9. How many spaces did you jump?"

Developmental Milestones

Beginning: Can find missing numbers in simple addition problems like 3 + ? = 5 using objects or fingers.

Developing: Solves missing number problems in both addition and subtraction within 10 without needing objects.

Proficient: Finds unknown numbers in various positions (start, change, result) within 20 using mental strategies.

Advanced: Explains their thinking and can create their own missing number problems for others to solve.

What to Look For

Understanding Equal Sign: Your child knows that = means "the same as" not just "the answer."

Flexible Thinking: Can solve ? + 4 = 9 as easily as 4 + ? = 9.

Strategy Use: Uses counting on, counting back, or fact families to find missing numbers.

Problem Solving: Can work with missing numbers in word problems, not just number sentences.

Below Grade Level

Focus on missing numbers in addition problems within 10. Use concrete objects and visual models. Start with the missing number at the end (3 + ? = 7) before moving to other positions.

Download Practice Worksheet

At Grade Level

Practice finding missing numbers in both addition and subtraction within 20. Work with missing numbers in all positions. Use mental math strategies and explain thinking.

Download Grade Level Worksheet

Above Grade Level

Challenge with missing numbers in more complex problems, including those with multiple steps or larger numbers. Create and solve their own missing number problems.

Download Challenge Worksheet