Addition and Subtraction Concepts 105Successful Strategies
The equal difference concept is applicable in any given
subtraction equation, but it is most effi cient when the created
expression invites mental math. For example, 73 – 25 = 74 – 26.
The created expression does not necessarily increase
opportunities for mental math. It is benefi cial for students
to think about when to use the equal difference concept and
when it may be better to use a different concept.
equal, difference, subtract,
subtraction, add, addition,
expression, equationMath Words to Use
Questions at Different Levels of Cognitive Demand
Recall: What is the difference between 52 and 39?
Comprehension: Which examples could you give of
the equal difference concept?
Application: How would you show the equal difference
concept on a number line?
Analysis: How are these expressions related?
Evaluation: Which problems work best with the equal
difference concept?
Synthesis: What if you were to create a new way to
record twice the difference?EASYCOMPLEX