Critical Thinking http://www.criticalthinking.org/page.cfm?CategoryID=51
History of Freedom of Thought http://www.criticalthinking.org/articles/history_freedom_of_thought.cfm
Improving Your Child's Thinking Skills Family Education has posted an article from the Council for Exceptional Children that gives examples of how to ask the right questions using the six major thinking skills defined by Bloom's Taxonomy. http://www.familyeducation.com/article/0,1120,59-11493,00.html
Critical and Creative Thinking Published by the Government of Saskatchewan, it includes definition, teacher's roles and types of questions to ask. http://www.sasked.gov.sk.ca/docs/policy/cels/el4.html
Teaching Thinking Skills Kathleen Cotton provides a detailed analysis of research on thinking skills. http://www.nwrel.org/scpd/sirs/6/cu11.html