In linear models of fractions, the length of the whole is divided into equal lengths.
A fraction is identified as being a particular distance from the 'start' of the whole.
Dividing strips of paper into equal lengths is an example of using a linear model to represent fractions.
Two or more of these strips placed side-by-side allows comparison of different fractions and identification of equivalent fractions. For example, it could be observed that half a strip is the same length as two-quarters of a strip.
Placing fractions on a number line uses a similar approach, but highlights the fact that some fractions occupy the same position on a number line and therefore represent the same quantity.
