Subtraction: The Same Difference Strategy
By Cindy Aossey (KCM) & Funda Gonulates (NKU)
Understanding how numbers can be adjusted while keeping the difference the same helps students
develop flexible strategies for subtraction. In this video, we demonstrate the Same
Difference
strategy using subtraction problems with two-digit and three-digit whole numbers, decimal, and
fractions. By adjusting both numbers in the problem by the same amount, students can transform a
more complex subtraction problem into one that is easier to solve mentally. To help students
understand why this works, we use the contextual example of two plants. By "shifting" both numbers
up, much like growing plants, we can create "friendly" numbers while preserving the original
distance apart. Seeing how the difference remains the same helps students build
number sense and
develop efficient strategies for subtracting larger numbers.
Targeted Standards: KY.2.NBT.5, KY.3.NBT.2, KY.4.NF.3, KY.5.NBT.7