A fraction bar (also referred to as the vinculum) is a bar that separates the numerator and the denominator of a common fraction. As shown below, the numerator is written above the fraction bar and the denominator is written below the fraction bar.
Fraction bars can also be written in different orientations, such as 1/12, or ½. The meaning of the bar is the same regardless of how it is written. It separates the numerator and denominator, and also indicates division. In a division problem, the fraction bar is the division symbol while the numerator is the dividend and the denominator is the divisor.
Modeling fractions with fraction bars
The term "fraction bar" is also used to refer to a visual representation of fractions using bars that are broken up into equal parts to depict different fractions. The figure below shows fraction bars for the fractions , as well as the number 1 (or 1/1).
1/1, or 1, represents one whole. Each subsequent fraction shows the size of the part relative to the whole. Fraction bars can be an effective visual aid for introducing students to the concept of fractions.