When using fraction strips, how do you know that two fractions are equivalent?

Fraction strips are bars drawn to show different fractions of unit such that one unit (a long bar) is drawn as two halves, and three thirds, and four fourths, and five fiths, and six sixths, and so on. To assess the equivalence of two fractions using fraction strips is very simple becasue you only need to put one strip below the other and see whether they have the same size or not. Two strips will have the same size if and only if the fractions are equivalent.

The slope of the function is 0.5.