Math Strategy: Using a Known Fact

What is the Math Strategy: 'Using a Known Fact'?

Math strategy: Using a Known Fact
Math strand: Number sense and numeration

Overview:
Using this addition and subtraction strategy students use a known fact that is closely related to the unknown fact to help them solve the equation. In the example from the video, 6+5 is unknown. The student thinks about a closely linked known fact, 6+4 = 10, then adjust the initial equation by one, and therefore the answer by one which would make 11.

Students may also commonly use a nearby double fact such as 6+6 or 5+5 to solve the problem, and adjust their solution accordingly.


How This Supports Student Learning:
Students who are using the known fact strategy are developing relational reasoning. They are beginning to work with numbers in more efficient and flexible ways, relying less on counting. They are continuing to build on part-whole relationships, recognizing that a first number (or part), plus a count of the second number (part), will give them the total amount (whole).


Where to Next:
As students build on their strategies for working with numbers in more and more flexible ways, they can begin to develop other strategies such as decomposing one or both addends to find anchors of five, for example 6+7 =(5+1) +(5+2)and then onto up and over 10, for example 7+5=(7+3) +2. Games such as Go fish 10, make 10 concentration, and handful of dice, from page 168- 171 from the ‘what to look for’ book by Alex Lawson can help children understand and see that smaller numbers make up larger numbers.

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