Sequels are not always lazy cash grabs. Sometimes they are successful additions to existing stories. “Sister Act 2: Back in the Habit” slaps much harder than its predecessor because it showcases Lauryn Hill, the struggles of underprivileged kids with creative aspiration and champions high school show choir long before “Glee.” Similarly, “Shrek 2” and “Spy Kids 2: Island of Lost Dreams” are the strongest installments within their respective four-part series. “Shrek 2” thoughtfully explores the strain new romance can place on old friendships and contemplates the significance self-love holds among societally dismissed people. “Spy Kids 2” strengthened the family-friendly kid film by addressing issues of maturation and purpose. Steve Buscemi plays a lonely geneticist named Romero, who poignantly ponders, “Do you think God stays in heaven because he too lives in fear of his own creation?” Robert Rodriguez challenges the children’s adventure genre by presenting existential musings into the sprightly mix. Sequels can be effective.

Adesola Thomas (20C) is from Hampton, Ga.