From Search to Research: Developing Critical Thinking Through Web Research Skills (PDF). A very useful e-book, understandably a little biased into Microsoft’s tools, particularly Bing, full of good references to critical thinking resources, accompanied with a vast selection of links to related sites.
From Conclusion: ‘The Internet is a river of information that seems to grow wider and flow faster every day. Web content, including this e-book, reflects this ongoing process of expansion and change. To stay current, you have to intentionally keep moving along with it. Online web literacy discussions are great places to find the latest tips, techniques, examples, and strategies for teaching students essential web literacy skills that help them develop as critical thinkers capable of engaging the world intelligently and creatively.’
Microsoft Teacher Guides: Critical Thinking in the Classroom. Applying critical thinking skills through web research can help students improve search skills, evaluate the information they find and incorporate them in their work. It contains a critical thinking and web research curriculum developed in cooperation with the International Society for Technology in Education (ISTE).
Critical Thinking Toolkit: a list of nine strategies for students to help them developing a practice of critical thinking. (Other study toolkits from this University of British Columbia site are also recommended)
Critical Thinking Compendium: a wiki about teaching critical thinking and Internet literacies maintained by Howard Rheingold and other educators.
Critical Thinking on the Web: a huge list of quality links to a wide variety of topics on this subject.