Subtraction as Finding the Difference

Subtraction has multiple meanings: taking away, counting back, and finding the difference. Comparison subtraction is essential for real-world problem solving.

• Framework: Montessori
• Unit: Mathematics
• Learning area: Operations
• Level: Ages 4-6

Objectives

• Understand subtraction as comparison
• Find difference between two quantities
• Build multiple meanings of subtraction

Materials

• Bead bars or number rods
• Comparison cards
• Recording sheet

Instructions

1. Place 8-bar and 5-bar side by side, aligned at left. 2. 'How many more is 8 than 5?' 3. Count the difference: 3. 4. 'The difference between 8 and 5 is 3.' 5. Record: 8 - 5 = 3. 6. Compare various pairs. 7. Word problems: 'I have 7 and you have 4. How many more do I have?'

Educator tip

This is different from 'taking away.' Both meanings are important. Use the word 'difference' frequently.

Assessment

Child finds differences by comparison and explains subtraction as finding 'how many more.'

More from Mathematics

• Cube Chains and Square Numbers
• Introduction to Simple Equations
• Mathematical Journal Writing
• Montessori Math Fair Projects
• Number Rods
• Sandpaper Numerals
• Spindle Boxes
• Cards and Counters