Number Bonds 1-20 (6-8 years)
Master number bonds to 20 with visual diagrams to strengthen mental math and addition fluency.
Materials Needed
- •Printed number bonds worksheet (download below)
- •Colored pencils or crayons (2 different colors work best)
- •Optional: Counters or blocks for hands-on exploration
Duration
15-20 minutes
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Why Number Bonds to 20 Build Math Fluency
Number bonds to 20 extend the foundational skills learned with bonds to 10, building mental math fluency essential for two-digit addition and subtraction. Research shows that children who understand these part-whole relationships develop significantly stronger number sense and can manipulate numbers flexibly without relying on counting. At ages 6-8, mastering bonds to 20 prepares children for more complex arithmetic, including addition with regrouping and mental calculation strategies. Understanding that 20 = 12+8, 15+5, or 11+9 helps children see patterns and relationships that make math more intuitive and less about memorization.
- check_circleAdvanced number sense: Understanding two-digit number relationships
- check_circleMental math fluency: Quick recall of addition facts to 20
- check_circleFoundation for regrouping: Understanding how to make tens when adding
- check_circleSubtraction mastery: Knowing 20-12=8 because 12+8=20
- check_circleProblem-solving flexibility: Using known facts to solve unknown problems
Preparation
Print worksheets on white paper. Have two different colored pencils ready for visual differentiation. If available, provide counters or a number line to 20 for hands-on exploration before moving to abstract representations.
Instructions
- 1
Connect to prior knowledge: "Remember how we made 10? Now we're making 20! It's the same idea, just with bigger numbers."
- 2
Start with doubles: "What's 10 + 10? That's right, 20! Let's find other ways to make 20."
- 3
Show the bond diagram: "Look at this number bond. The big circle shows 20. The smaller circles show the two parts that combine to make 20."
- 4
Work through examples: "Let's try 12 + 8. Count it out if you need to. Yes! 12 and 8 make 20!"
- 5
Look for patterns: "Notice something? 11+9, 12+8, 13+7. As one number goes up by 1, the other goes down by 1!"
- 6
Practice both ways: "If you know 15+5=20, then you also know 5+15=20. Same partners, different order!"
- 7
Real-world connection: "You have 20 candies. You eat 12. How many are left? 8! Because 12+8=20."
Assistance for Kids and Parents
- arrow_rightBuild on tens: "If you know 10+10=20, then 11+9 is just one more and one less from each 10."
- arrow_rightUse money: "Two dimes make 20 cents. What about a dime and 10 pennies? Still 20!"
- arrow_rightMake it visual: Use two different colored blocks arranged in groups to show the bonds visually.
- arrow_rightPractice daily: Spend 5 minutes each day reviewing different bonds. Consistency builds automaticity.
- arrow_rightConnect to time: "There are 20 minutes left. 12 minutes for homework, 8 for play. That's 20!"
- arrow_rightPlay card games: Draw two cards, try to make 20. "I have 7, what card do I need? 13!"
- arrow_rightCelebrate strategies: "You didn't count! You just knew 15+5=20. That's mental math!"
Variations & Extensions
Speed Challenge
Time how long it takes to write all number bonds to 20. Practice daily to improve speed and build automaticity. Track progress on a chart.
Missing Number Problems
Write problems with missing numbers: "__ + 8 = 20" or "13 + __ = 20". This develops algebraic thinking and reinforces inverse relationships.
Real-World Word Problems
Create story problems: "Sarah has 20 stickers. She gives 13 to her friend. How many does she have left?" Draw the number bond to solve.
Extend to Larger Numbers
Once 20 is mastered, explore bonds to 50 or 100 (using multiples of 10). "30+70=100, 40+60=100."