There is a fantastic new book just published that covers Jesus and the gospels, canonical as well as extracanonical. Vernon Robbins,
Who Do People Say I Am? Rewriting Gospel in Emerging Christianity
Professor Robbins' book is the best there is on the market in my opinion. I highly recommend it to you, especially if you are looking for a book to teach this subject.
Robbins sets the more commonly known representations of Jesus in the Bible alongside lesser-well-known portraits of him found in texts like the Gospel of Thomas, the Gospel of Mary, the Gospel of Judas, and the Acts of John. He does this, not simply as a rehash of general knowledge, but applying all of his years of accumulated knowledge of orality, rhetoric, cognition and the social fabric of Christianity to the material. You are face-to-face with Robbins the veteran professor sharing generously his knowledge.
The book is very accessible in terms of style and yet very careful in terms of historical detail. A perfect match for the non-specialist reader, and specialists from other areas of New Testament study who want to get a handle on the extracanonical material.