Definition
Number bond
A number bond is a part–whole diagram showing how one number is composed from smaller numbers.
What it means
Put the whole in one circle and its parts in the connected circles. With whole 10 and parts 6 and 4, the bond records that 6 and 4 make 10. You can use the same relationship for addition or subtraction; the branches do not point in a calculation direction.
Remember it
One whole, connected parts: the parts fit together to make the whole.
Example
A bond with 15 as the whole and 8 and 7 as the parts shows 8 + 7 = 15. It also supports 15 − 8 = 7 and 15 − 7 = 8. The diagram stays the same because the part–whole relationship stays the same.
Watch for
Three numbers linked in any shape are not automatically a number bond; one must be the whole and the others must be its parts.
Common mix-up
A number bond is not an equation and does not itself choose addition or subtraction; it displays the relationship those equations use.
Exact meaning
A number bond is a part–whole representation that connects one whole to two or more non-overlapping parts whose values combine to equal the whole.