In The Prime of Miss Jean Brodie, Muriel Sparks handles time in accord with modernist and postmodernists approaches. These contradict traditional conventional approaches to time. The convention relating to time in traditional novels is to present time as a chronological event. In modernism and postmodernism the chronology becomes broken and fragmented to reflect individuals' experience of time in their private thoughts (thoughts may jump from 1952 to 2021 in the space of a few minutes or even seconds). For modernists and postmodernists, fragmentation of time causes discontinuity. This discontinuity effects the development of character as well, leaving characters fragmented along with time.
Another element that Sparks uses from the approaches of modernists' and postmodernists' approach to time is to have events from the end of the time period the novel covers break into the "present" narrative. This is not by means of conventional foreshadowing whereby an event is hinted at for perceptive readers to pick up on and to give the "feeling" of impending turns and twists in events to any reader. Sparks has the future break in to the present in actual scenes and conversations. A clear example of this is when Brodie's former students, one by one, speak about Brodie from a distant time, as with Sandy speaking of her after she has become a famous psychologist and author. This technique is called a flash-forward. Sparks also uses flashbacks, a technique people are more familiar with as it is more commonly used to tell a back story (frequently seen in movies). In flashbacks, events prior to the commencement of the novel's chronological tale intrude into the story to give details relevant to understanding the subject of the novel.
It is interesting to note that traditionalist novelists like Tolstoy would call future events into a present narrative by way of "framing" as Tolstoy did in The Death of Ivan Ilyich, but in contrast with modernists and postmodernists, Tolstoy used a future frame to establish continuity, whereas modernists and postmodernists use the future and the past to create discontinuity. Incidentally, the major distinguishing feature separating modernists from postmodernists is that the former mourn the fragmentation and discontinuity of life and experience (e.g., Virginia Woolf) whereas the latter celebrate the fragmentation and discontinuity of life and experience and seek to exploit it and utilize it seeing as how it can't be gotten rid of (e.g., Sparks).