Textbook chapter numbers: possible confusion

We are using the OpenStax textbook Calculus, by Gilbert Strang, Edwin Herman, et al. The book covers single-variable and multivariable calculus, and it has 17 chapters. It is published in three volumes, with a few chapters included in two volumes:

Volume 1: single-variable differential calculus and the beginning of integration, chapters 1-6
Volume 2: single-variable integral calculus and infinite sequences and series, chapters 5-11
Volume 3: multivariable calculus, chapters 11-17

To make things confusing for us, within each volume, the included chapters are renumbered starting with chapter 1. So if you look at the whole textbook, you see a different chapter number than if you are reading a single volume of the textbook (except they match for Volume 1 chapters).

Textbook chapters covered in Math 1C

These are the specific chapters that we will be studying in Math 1C, listed in the order that we will cover them:

Chapter 12: Vectors in Space
Chapter 14: Differentiation of Functions of Several Variables
Chapter 9: Sequences and Series
Chapter 10: Power Series

Taken from volumes 3 and 2 and placed into Canvas, these chapters are numbered (in our order of study) 2, 4, 5, 6. Each Module that follows is titled with a Calculus textbook chapter numbered from the individual volumes, so Modules go as chapters 2, 4, 5, 6 in order; but in each chapter title, the chapter number from the overall textbook is also listed for reference.