Mattie, who at 15 is the youngest competitor this season ... will air on American Idol‘s April 7 episode. It will cut the remaining field by more than half to complete the Top 24.

Spoiler alert! Twelve of the Top 24 'American Idol' hopefuls take the stage in Hawaii to earn a spot in the Top 20.

Now that the second group of 12 have performed, next Sunday night, the Top 20 will be revealed in a three-hour special episode of American Idol. Related: American Idol 's Top 24 Perform for America's ...