Sometimes it can be a challenge to know exactly what to cover in the introductions to the units/chapter/general topics in an anthology and to the individual readings. Authors may feel uncertain about the right language to use, or struggle to hit the right note stylistically, as they try to introduce multiple readings without repeating the same language over and over.
Having the right language at hand and preparing several ways to say similar things before beginning to write can facilitate the writing process and make the reading experience a better one for students.
Other resources that may be helpful to you include:
Editor’s Toolkit: Introduction to the Chapter
Editor’s Toolkit: Writing Introductions for Readings in an Anthology