Skill: Identify fourths

A fourth is one of four equal parts of a whole. We write it as $\frac14$.

Example: A rectangle is divided into 4 equal-size parts. One part is shaded.

To decide whether the shaded part is a fourth:

1. Look at the entire rectangle. This is the whole.
2. Count the parts: there are $4$ parts.
3. Check that the parts have equal area. They are all the same size.
4. Since the shaded part is 1 of the 4 equal parts, it is $\frac14$, or one fourth.

All four parts together make one whole:

$$\frac14+\frac14+\frac14+\frac14=\text{one whole}$$

If the rectangle were divided into 4 parts of different sizes, the parts would not be fourths because fourths must be equal.