Any edition of the Student Workbook for Essentials Units 16-22 that is from the 2nd Edition (2018) or later has the same lesson content and may be used with any 2nd Edition or later Teacher's Guide for these seven units. Currently the 2nd Edition is the newest version of both of these books.
However, note that books from the 1st Edition of Essentials (published in 2012) are not compatible with newer versions.
Detailed Edition History: Essentials 16-22 Student Workbook
1st Edition: Essentials Cursive Workbook and Essentials Manuscript Workbook: Published in 2012; out of print, but available digitally. 480 pages. All of Essentials (40 lessons) in one book. Single level of application in each lesson. Provided sample answers in cursive or manuscript to model good handwriting.
Compatible only with the Essentials Teacher's Manual, 1st Edition (2012).
2nd Edition: Essentials 16-22 Student Workbook. Published in 2018. 212 pages. The third quarter of the updated and expanded Essentials. Includes three levels of application in each lesson.
Compatible with any 2nd Edition or later Teacher's Guide for Essentials Units 16-22.
Not compatible with the Essentials Cursive or Manuscript Workbook, 1st Edition (2012).