"Most instructors are used to having a curriculum handed to them in textbook form." What evidence do you have to back up this assertion? This is most definitely not my (or my colleagues) experience over the last 15 years.
Limiting a ToK class to one source would be utterly disastrous and totally against the entire aims of the programme.
The Role of ToK is NOT to "try to teach students how to think".
Sure. But without identification of where the problem lies how can we even begin to address the issue?
It appears that students are coming out of the Diploma programme without a basic understanding of what ToK is, let alone a good grounding in it. The IBO could not be any clearer on what ToK is, what the aims and objectives are and how it should be approached.
As an IB teacher (of 15 years) and examiner I can confidently say that the problems identified in this thread have two points of origin: 1) Schools don't care about the implementation of ToK in relation to the major subject areas and 2)in general teachers don't know (and don't care to find out) how to teach it.
The IBO is very clear about what ToK should be. The blame lies at the feet of institutions who don't value ToK and treat it as a barely acknowledged addition to the diploma.
Theory of Knowledge can (and should be) great. The fact that many schools force apathetic teachers to "teach" it is where the problem lies. All IB teachers are REQUIRED to integrate ToK into their subjects and almost none do. Most IB teachers do not have the first clue what ToK is and they are not motivated to find out.
I have noticed that few commenters here seem to be aware of the actual aims and objectives of the course (based on their comments here). Perhaps reading page 5 of the ToK guide would be pertinent for those who think ToK is "pointless" or for those who thought that "ToK sucks".
ToK is NOT about "solving problems" - it is to encourage thinking critically about knowledge, expressing ones own views, sharing ideas and developing ideas about "knowledge as a human construction".
That is all.
EDIT: What's the deal with downvotes? As a new member of the community what's the protocol?