How does the author use foreshadowing in Bad Influence?

At fifteen, Rita, the narrator, is at odds with the world of her Puerto Rican grandparents, whose eccentric, old-fashioned ways strike her as ridiculous. A typical teenager, she is hypercritical of the adults around her, and finds them invasive and disrespectful of her boundaries. Rita has been sent to the island to stay with her grandparents to keep her out of trouble with boys. Initially she is brutally caustic and critical. This foreshadows conflicts between Rita and her grandparents during her stay there.