Here is the primary resource that I am reading (A Quick Guide To Boosting English Acquisition in Choice Time by Alison Porcelli & Cheryl Tyler) to think about Choice Time Workshop.
In this book the authors explain the idea of a Choice Workshop in this way:
“The phrase— choice time workshop—implies not only that children are invited to play with blocks and construct art projects but also this time adheres to the structures of workshop teaching. Workshops—whether reading workshops, writing workshops, or choice time workshops—are designed to provide learners with long chunks of time so that they have the opportunity to plan, to construct, to revise, and to share work. Choice time workshops not only provide children with opportunities for extended independent work, but these workshops also provide children with explicit instruction from a teacher.”