Fractions

Adding and subtracting fractions with the same denominator rests on seeing a fraction as so many parts of a 1 cut into equal pieces. Cases where the answer is 1, and cases that take a fraction away from 1, are both included, and word problems plus Two Steps (Word Problems) tie situations to expressions.

Adding the denominators as well, so that 1/5 + 2/5 becomes 3/10, is the standard error. A changed denominator in the answer identifies it. For 1 - 2/5, children cannot rewrite the 1 as 5/5, and answers such as 1/5 or 2/4 are left standing.

Fractions do not appear as a unit in any earlier grade, so this is the first encounter with them. Building on this experience of meeting a new way of writing a number, different from whole numbers and decimals, the range covered widens further in Fractions in grade 4.