The authors Carol Rainbow and Christel Schneider published a book entitled: Making and using Machinima in the language classroom, available through The Round on Amazon and SmashWord
Creating and using machinima in the language classroom is a guide to encourage teachers and learners to create videos in virtual worlds (machinima) for enhancing language lessons.
Although the book is not specifically about learning or teaching in virtual worlds it does help and gives instructions for the reader to access and be able to use Second Life for the purpose of machinima making.
Interested? Here you will find more about the content: http://the-round.com/resource/making-and-using-machinima-in-the-language-classroom/
https://www.amazon.com/Virtual-Worlds-Language-Learning-Telecollaboration/dp/3034305737
https://www.igi-global.com/chapter/learning-by-doing-in-3d-environments/182026