A number bond is a tried-and-true triangular math tool that is simple to explain and understand. It is a visual image that shows children the relationship between a number and the parts that combine to make that number: part-part-whole. This helps children solidify their understanding of foundational addition and subtraction math skills, rather than relying on rote memorization of fact families.

Children can see how the numbers join together to form a new number (compose) and how that number can be split into separate numbers (decompose). The number bond is a three-circle triangle—the circle that connects to both parts is the sum of the other numbers. This shows the commutative property of addition. You can swap the order of the parts and they still provide the same sum: 3 + 4 = 7 and 4 + 3 = 7. This can be displayed in different shapes, like circles or squares, and in different positions:

  • Sum on top and addends underneath
  • Sum to the left and addends branching out to the right
  • Addends on top and the sum below
  • Addends to the left and sum branching to the right

Most importantly, children are able to see the relationship of the numbers. This one simple image is so impressive because it shows the relationship of addition and subtraction:

Number bonds are used in Common Core State Standards in kindergarten (K.OA.4, K.OA.5), first grade (1.OA.B.3, 1.OA.B.4, 1.OA.C.6), and 2nd grade (2.OA.B.2, 2.NBT.5). It was created in Singapore and is used as a foundational tool for Singapore Math (which aligns to Common Core State Standards). It is also used by Eureka Math and Engage NY math programs.

Number Bond Answer Boards (LER 5213) are perfect for classroom work. They can be used to give the teacher a bird’s-eye view of how well the class is understanding the concept and who needs a little more assistance, without drawing negative attention to any student(s). Number Bond Answer Boards are also great for individual practice, quick assessments, and quizzes. And, because they are write & wipe, they save time and are reusable, providing an environmentally friendly alternative to paper.