From basic through advanced grammar concepts, the Purple Workbook provides clear definitions of rules, repeated examples, and plenty of practice. Step-by-step instructions and regular review help every student succeed

You may notice that the Workbooks and Keys for this curriculum are now named by color (“Purple Workbook”) rather than by year (“Year 1”). That’s to help you understand that you can use these workbooks in any order. It’s a four-year cycle but the books can be done in any order. The Core Instructor Text still provides the instructions for all four years.
If you have one of the older copies that says “Workbook 1” instead of “Purple Workbook,” don’t worry; the content is still the same.

WTM Press