Definition
Fraction addition
Fraction addition combines fractional amounts that refer to compatible wholes or the same unit.
What it means
Before combining fractions, make sure the amounts describe the same-sized whole or unit. If the pieces are already the same size, add how many pieces there are. If not, rename the fractions as equivalent fractions with matching-sized pieces.
Remember it
Match the piece size, then count the pieces.
Example
Maya walks 3/8 mile in the morning and 2/8 mile later. The parts are the same size, so 3/8 + 2/8 = 5/8 mile.
Watch for
One third of a small pizza plus one third of a large pizza is not automatically two thirds of one pizza; the whole must be defined.
Common mix-up
Do not add the denominators. A denominator names the part size; the numerator counts those parts.
Exact meaning
Fraction addition combines two or more fractional quantities that refer to compatible wholes or the same unit. Like-denominator fractions combine counts of equal-sized parts; unlike denominators must first be expressed with compatible part sizes.