Mathematics · Year 1 · Additive Reasoning · Autumn Term

Number Bonds to 20

Extending knowledge of number bonds to numbers up to 20.

• National Curriculum Attainment Targets
• KS1: Mathematics - Addition and Subtraction

About This Topic

Number bonds to 20 build directly upon the foundational understanding of number bonds to 10, a crucial skill for Year 1 mathematicians. This topic focuses on exploring the various pairs of numbers that sum to any given number up to 20. Students will learn to systematically identify these combinations, moving beyond rote memorization to a deeper conceptual grasp of number relationships. For instance, they will discover that if they know 5 + 5 = 10, they can use this to find bonds for numbers greater than 10, such as 10 + 5 = 15.

Developing fluency with number bonds to 20 is essential for efficient addition and subtraction within 100. When students can quickly recall that 7 + 8 = 15, they can more easily solve problems like 15 - 7 or 25 + 7. This topic also encourages reasoning about number patterns and structures. Comparing number bonds to 10 with those to 20 helps students articulate how their understanding of smaller numbers informs their knowledge of larger numbers, fostering early algebraic thinking. This conceptual understanding is key to future mathematical success.

Active learning significantly benefits the development of number bonds to 20. Hands-on activities allow students to physically manipulate objects, visualize relationships, and discover patterns independently. This concrete experience makes abstract number concepts tangible and memorable, solidifying their understanding in a way that passive instruction cannot.

Key Questions

1. Compare number bonds to 10 with number bonds to 20.
2. Construct all possible number bonds for the number 15.
3. Justify why knowing number bonds helps with addition and subtraction.

Watch Out for These Misconceptions

Common Misconception

Students may think there is only one way to make a number, like 10 + 5 for 15.

What to Teach Instead

Using manipulatives like counters or number lines allows students to physically explore and discover all possible combinations, reinforcing that numbers can be partitioned in multiple ways. Collaborative sharing of findings helps expose students to different bonds.

Common Misconception

Confusing addition bonds with subtraction facts.

What to Teach Instead

Activities that involve both addition and subtraction, such as using part-part-whole diagrams or fact families, help students see the inverse relationship. Demonstrating how 8 + 7 = 15 also means 15 - 7 = 8 clarifies this connection.

Active Learning Ideas

Number Bond Match-Up: Cards

Create sets of cards, with one card showing a number (e.g., 13) and others showing pairs that sum to it (e.g., 10+3, 9+4, 8+5). Students work in pairs to match the number cards with their corresponding bond cards.

20 min·Pairs

Building Towers: Number Bonds

Provide students with two colors of building blocks. Ask them to build towers of a specific height (e.g., 15 blocks) using only two colors. They record the number of blocks of each color used, creating a visual representation of a number bond.

25 min·Individual

Number Bond Hopscotch

Draw a hopscotch grid with numbers up to 20. Students hop to a number, then call out two numbers that add up to it. For example, landing on 17 might elicit '10 and 7' or '9 and 8'.

15 min·Whole Class

Frequently Asked Questions

Why are number bonds to 20 important for Year 1?

Number bonds to 20 are foundational for developing fluency in addition and subtraction within 100. They help students decompose and recompose numbers, which is crucial for mental math strategies and understanding place value. This skill supports more complex calculations later on.

How does knowing number bonds to 10 help with number bonds to 20?

Students can use their knowledge of bonds to 10 as a stepping stone. For example, knowing 7 + 3 = 10 can help them figure out 7 + 13 = 20 by recognizing that 13 is 10 + 3. This builds confidence and shows them how to extend known facts.

What is the difference between number bonds and addition facts?

Number bonds focus on the relationship between a whole number and its parts, showing all the ways a number can be made. Addition facts are specific equations showing the sum of two numbers. Number bonds provide the conceptual framework for understanding addition facts.

How can games make learning number bonds to 20 more engaging?

Games transform practice into play. Activities like 'Number Bond Bingo' or 'Memory Match' with pairs that sum to 20 encourage repeated practice in a fun, low-pressure environment. This active engagement helps students internalize facts and relationships more effectively than rote drills.