The Bell Jar
The Bell Jar is a novel by Sylvia Plath. In the beginning of the movie, there is a scene in which Kat is reading The Bell Jar in her house, just before her father confronts her about the damage she did to Joey's car. The book symbolizes Kat's feminist perspective (Plath is widely known as a feminist poet whose work expresses mistrust in men) as well as her commitment to being a social outsider.
Shakespeare
William Shakespeare is a recurring motif in the film: Mr. Morgan's sonnet-writing assignment is based on Shakespeare's poetry, and Kat's best friend Mandella is a Shakespeare aficionado who quotes him regularly. The prevalence of the Bard in the film is not surprising, as the plot of the film itself is based on Shakespeare's play The Taming of the Shrew.
The Guitar
At the end of the film, Patrick purchases a brand new guitar for Kat, using the money that Joey had paid him to date her. The guitar symbolizes Patrick's acknowledgement of his mistake and his desire to make amends with Kat. It also signifies his care for her, as he had seen her playing the guitar in the shop earlier in the film.
Pearl Necklace
The pearl necklace that Bianca wears in the film belonged to Kat and Bianca's mother. When Kat confronts Bianca about it, she is visibly upset. The necklace symbolizes the girls' connection to their mother, which has been reduced to a mere object since she left the family (a fact that is only mentioned peripherally in the film). Bianca's retort that their mother "is not coming back to claim [the pearls]" emphasizes the sense of loss that both daughters have experienced, while also pointing toward a reason why their father may be so overprotective.
The Sonnet
At the end of the film, Kat delivers her own sonnet that she had written as part of Mr. Morgan's English assignment. The sonnet is about all the things she hates about Patrick (hence the title of the film), but the poem ultimately reveals that Kat is still in love with him. The sonnet symbolizes both the film's connection to its source material (Shakespeare's play), as well as Kat's transformation from a man-hating cynic to a heartbroken young woman.
