Skills Covered

How to Use This Worksheet

Each problem shows a fact family triangle with three numbers and four equations where some numbers are missing. Students use the triangle to determine each missing value, building early algebraic thinking skills.

In the Classroom

Use after students have practiced writing all four facts. The missing-number format challenges students to think more deeply about fact family relationships. Great for differentiated instruction - pair with the "Write All" version for struggling learners.

At Home

Cover one of the three numbers in the triangle and ask your child to figure out which number is missing. Then have them complete the equations. This builds problem-solving skills in a structured way.

Tips for Success

• Remind students to look at the triangle for all three numbers
• Encourage checking answers by substituting back into the equation
• Start with problems where only one number is missing, then try two
• Use the answer key for self-checking

Common Core Standards Alignment

This worksheet supports the following Common Core State Standards for Mathematics:

• 1.OA.B.4 - Understand subtraction as an unknown-addend problem
• 1.OA.D.8 - Determine the unknown whole number in an addition or subtraction equation
• 1.OA.C.6 - Add and subtract within 20, demonstrating fluency within 10