Counting Back: Start from the larger number and count backward by the amount of the smaller number
- Start at the larger number
- Count backward one number at a time
- Count the same number of steps as the subtracted number
- The final number is the answer
• Count each step carefully
• Move left on the number line
• The number of steps equals the number being subtracted
Number Bonds: Using known addition facts to solve subtraction problems (inverse relationship)
If: 5 + 3 = 8, then: 8 - 3 = 5 and 8 - 5 = 3
Use known addition facts to find subtraction answers
• Addition and subtraction are inverse operations
• Use known addition facts to solve subtraction
• Practice addition facts regularly
Compensation: Adjust numbers to make calculation easier, then adjust the answer
Round the subtracted number up to the nearest ten, subtract, then add back the difference
• Round to the nearest ten for easier calculation
• Remember to add back the difference
• Compensation works well for numbers close to 10
- Counting Back: Move backward on number line
- Number Bonds: Use addition facts for subtraction
- Compensation: Adjust numbers to make calculation easier
- Doubles Facts: Use known doubles for related subtraction
- Decomposing: Break apart numbers strategically
• Commutative Property: Does NOT apply to subtraction (a - b ≠ b - a)
• Associative Property: Does NOT apply to subtraction
• Identity Property: a - 0 = a
• Inverse Operations: Addition and subtraction undo each other
- Subtracting 1-3: Use counting back
- Subtracting 4-5: Counting back or number bonds
- Subtracting 6-7: Number bonds or decomposition
- Subtracting 8-9: Compensation (think 10 and adjust)
- Doubles: Use doubles facts (12-6, 16-8)
Doubles Facts: Use known doubles (like 6 + 6 = 12) to solve subtraction
When you subtract one of the doubles from the total, you get the other double
Examples: 8 + 8 = 16 → 16 - 8 = 8
• Memorize basic doubles (1+1, 2+2, ..., 10+10)
• Doubles subtraction gives the same number
• Practice doubles regularly for quick recall
Decomposing: Break apart the number being subtracted into smaller, easier-to-manage parts
Break the subtracted number into parts that are easier to subtract
Example: 13 - 6 = 13 - 3 - 3 = 10 - 3 = 7
• Break complex problems into simpler ones
• Choose parts that make subtraction easier
• Practice decomposing numbers regularly
Minuend: The number being subtracted from (the first number)
Subtrahend: The number being subtracted (the second number)
Difference: The result of the subtraction
Mental Math: Calculating in your head without writing
Number Bonds: Pairs of numbers that add up to a given total
- Analyze the numbers: Look for relationships (doubles, near doubles, round numbers)
- Choose the strategy: Counting back, number bonds, compensation, doubles, or decomposition
- Apply the method: Follow the steps of the chosen technique
- Verify the result: Check by adding the difference to the subtrahend
• Counting Back: For small subtrahends (subtracting 1-5)
• Number Bonds: For problems with known addition facts
• Compensation: For numbers near 10 (9, 8, 11, 12)
• Doubles Facts: For doubles subtraction (like 12-6, 14-7)
• Decomposition: For breaking apart complex subtrahends
- Week 1-2: Focus on counting back strategy
- Week 3-4: Introduce number bonds
- Week 5-6: Practice compensation
- Week 7-8: Work on doubles facts
- Week 9-10: Combine all strategies