Question: what is between 1/4 and 2/4?
Answer: The example fractions of 1/2, 2/3 and 3/4 with common denominators become 6/12, 8/12 and 9/12. The numerator 8 is between 6 and 9, so the fraction you created – 8/12, or 2/3 when simplified – is between the two fractions you started with.