Anne throws herself into her writing and studies while in hiding. She mentions writing poems and short stories, sometimes as gifts for the other people in hiding with her. And obviously, she writes and edits her diary in her spare time. She also studies short-hand, English, French, history, algebra, religious topics, and other academic topics.
Reading is also a major past-time. From movie magazines to history books, Anne devours whatever she can get her hands on. Anne is a bit frustrated that her parents are very strict about what she is allowed to read, since they are nervous about her perusing material dealing with "adult" topics.
Later on, Anne forms a friendship with Peter van Daan and the two spend large amounts of time talking alone together, though the adults become concerned that their doing so is improper.