The Foundation for Critical Thinking provides a free library of articles about the theory and practice of Critical Thinking. The articles fall under the following headings: About Critical Thinking, Fundamentals of Critical Thinking, Documenting the Problem, Higher Education Strategies & Samples, K-12 Strategies & Samples, For Students, Interviews & Editorials, Issues in Critical Thinking, and The Questioning Mind. Some of the material may seem basic, and much of it might be remedial for experienced educators. However, the clarity of the writing and the formulation of useful lists and frameworks make the articles good resources for thinking about how educational Websites can better engage users in thinking critically. Below are a few of the articles offered on the site:

A Brief History of the Idea of Critical Thinking
An overview of the intellectual history of Critical Thinking from Socrates through Aquinas, Bacon, Descartes, Hobbes, Locke, Newton, Boyle, Smith, Kant, and Darwin. It concludes with a list of the basic foundations of knowledge and reasoning that can be brought into question through Critical Thinking:
    * ends and objectives,
    * the status and wording of questions,
    * the sources of information and fact,
    * the method and quality of information collection,
    * the mode of judgment and reasoning used,
    * the concepts that make that reasoning possible,
    * the assumptions that underlie concepts in use,
    * the implications that follow from their use, and
    * the point of view or frame of reference within which reasoning takes place.

Glossary of Critical Thinking Terms
A glossary of terms used in discussing thinking, reasoning, and knowledge, defined in the context of Critical Thinking.

Becoming a Critic Of Your Thinking
A tutorial on the art of Critical Thinking. The tutorial provides four key tips:

1) Clarify Your Thinking:
articulate one point at a time and elaborate, using examples, and creating metaphors and analogies when needed to relate you thoughts to actual experience

2) Stick to the Point
Stay focused on what is relevant to the primary question at hand, avoiding associations that distract from the logical connection of thoughts.

3) Question Questions
determine the most precise, accurate, and relevant  questions by formulating your questions in different ways

4) Be Reasonable
Be open-minded and willing to change your thinking when presented with better reasoning.

The article also provides a list of behaviors that work against critical thinking, including jumping to conclusions, failing to notice our assumptions, misusing words, asking loaded and/or irrelevant questions, among others.

Open-Minded Inquiry: A Glossary of Key Concepts
The author Identifies open-mindedness as one of the fundamental goals of education, an idea derived from the work of John Dewey and Bertrand Russell. He then offers a Glossary of terms such as Assumptions, Bias, Dogmatism, Judgment, Neutrality, Relativity, and Uncertainty, among others, defining them in relation to the goal of engaging in inquiry with a critical, open mind.

Tactics that Encourage Active Learning
Ask students to do the following:
1.  Summarize or put into their own words what the teacher or another student has said.  
2. Elaborate on what they have said.
3. Relate the issue or content to their own knowledge and experience.
4. Give examples to clarify or support what they have said.
5. Make connections between related concepts.
6. Restate the instructions or assignment in their own words.
7. State the question at issue.
8. Describe to what extent their point of view on the issue is different from or similar to the point of view of the instructor, other students, the author, etc.
9. Take a few minutes to write down any of the above.
10. Write down the most pressing question on their mind at this point. The instructor then uses the above tactics to help students reason through the questions.
11. Discuss any of the above with a partner and then participate in a group discussion facilitated by the instructor.