3/8 is bigger than 5/16 (even though 5 is bigger than 3)
3/16 is bigger than 1/8 (even though 16 is bigger than 8)
See the Comparing Fractions page for lessons and information about how to tell which is the larger of any two fractions.
Practice and study
Use these search terms to find your own resources:
ordering fractions
putting fractions in order
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