I saw it in a self-study textbook taught by others.

Sequential narrative, also known as positive narrative, is a kind of narrative method. Sequential narration is a method of narration according to the time sequence of events. The advantage of this narrative method is that the events are orderly from beginning to end, with natural style and coherent articles. When using the sequential method, we must pay special attention to tailor our measures to ensure proper details and clear priorities. It is a common narrative method in narrative literature.

Flashback is a method to bring the ending of an event or the most important and prominent fragment to the front of the article according to the needs of expression, and then describe the event from the beginning in the original development order.

Insertion is a narrative method in which narrative clues are temporarily interrupted and memories or stories related to the main plot are inserted in order to help the development of the plot or the characterization of the characters in the process of narrative central events.

A straightforward narrative is a parallel narrative, which describes two or more things that happen in different places at the same time. Usually, one thing is described first, and then another thing is described, which is called "how many flowers bloom, one for each table", so it is also called separate narration.

References:

People's Education Publishing House's Chinese self-reading textbook (the first volume of Grade 8), The Stars in the Day, Chapter 80, Mastering Common Narrative Methods