Definition
Derived fact
A derived fact is a new number fact worked out from a fact you already know.
What it means
Start with a fact you trust. Then make one clear mathematical change and change the answer in the matching way. You are not guessing or starting again; you can point to the known fact and explain the link that creates the new fact.
Remember it
Build the new fact on a fact you know, using one matching change.
Example
I know 6 + 6 = 12. In 6 + 7, the second addend is one greater, so the total is one greater too: 6 + 7 = 13. That makes 6 + 7 = 13 a derived fact from the double 6 + 6.
Watch for
Remembering 6 + 7 = 13 without using or explaining a known relationship recalls a fact, but it does not show how the fact was derived.
Common mix-up
The change must preserve the relationship: adding one to an addend adds one to the sum, but it would not add one to a product.
Exact meaning
A derived fact is a number fact obtained from one or more known facts by applying a valid mathematical relationship, such as one more, one less, doubling, making ten, place value, or inverse operations.