Tired of being overlooked because he is so small, Dexter, a big-hearted dog with big dreams transforms himself into a superhero. Martha Speaks Reading Buddies Interest Level: K-3 Reading Level: 3.5 ATOS Book Level: 3.5 AR Interest Level: LG AR Points: .5 AR Quiz: 76675EN Reading Counts Level: 2.5 Reading Counts Points: 1 Lexile Measure: 740 Lexile Code: AD (Adult Directed).