you could research bilingualism and how that affects a person's ability to learn; you could study how language affects or shapes a culture. i only learned briefly about it in psychology, but my professor mentioned that one's native language can shape their attitudes and such. in regards to language acquisition, you could create a presentation that talks about how easy it is to learn a language at different ages--you know, how brain elasticity is at its peak at certain ages and how there's an ideal time to acquire your second language in childhood.