Fact Family Triangles

Fact families explicitly connect addition and subtraction, showing children that four related facts share the same three numbers.

• Framework: Montessori
• Unit: Mathematics
• Learning area: Operations
• Level: Ages 5-6

Objectives

• Understand inverse relationship of addition and subtraction
• Build all four related facts
• Develop algebraic thinking

Materials

• Fact family triangle cards
• Bead bars for verification
• Recording sheet

Instructions

1. Present triangle with 3, 5, 8. 2. 'What addition facts can you make? 3+5=8, 5+3=8.' 3. 'What subtraction facts? 8-3=5, 8-5=3.' 4. 'These four facts are a fact family!' 5. Verify each with bead bars. 6. Complete blank triangles. 7. Find the missing number: 4 + ? = 9.

Educator tip

The triangle format (total at top, parts at bottom) reinforces the part-part-whole relationship across all four operations.

Assessment

Child creates complete fact families and uses them to find missing numbers.

More from Mathematics

• Introduction to Negative Numbers
• Multiplication as Arrays
• Introduction to Elapsed Time
• Subtraction as Finding the Difference
• Cube Chains and Square Numbers
• Introduction to Simple Equations
• Mathematical Journal Writing
• Montessori Math Fair Projects