Start with equal parts
A fraction describes part of one whole. The lower number tells how many equal parts make the whole; the upper number tells how many of those parts are selected. If a bar has four equal parts and one is shaded, the shaded share is one fourth.
Then compare shares
Two fractions can name the same amount even when they use different numbers. One half and two fourths both cover half of a bar. Count or compare the equal parts rather than choosing the fraction with the larger numbers.