A mathematical explanation connects a problem’s quantities and relationships to a representation, equation, and answer, describing what each number means, why a chosen operation models the situation, and how the calculation supports the result. At this level, explanations involve whole-number addition and subtraction within 1,000 and introductory equal-group or sharing situations; formal algebraic proofs, generalized rules, and explanations involving larger or more abstract numbers are not included.
When you explain a solution, tell what the numbers mean, describe the action in the problem, write an equation, and state what the answer means.
Example:
Mia has 64 crayons. She gives 28 crayons to a friend. How many crayons does Mia have left?
Identify the quantities.
Choose an operation.
Mia gives crayons away, so the amount gets smaller. We use subtraction:
Solve the equation.
Subtract first, then subtract :
So,
You can check the answer by adding the crayons left and the crayons given away:
This matches the starting amount, so the answer makes sense.
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