Cornell Conditional Reasoning Test (1964), by Robert H. Ennis, William Gardiner, John Guzzetta, Richard Morrow, Dieter Paulus, and Lucille Ringel. Illinois Critical Thinking Project, Champaign, IL. Available at no cost. Developed for research purposes, but usable in standard classrooms. The research report with considerable data is Critical Thinking Readiness in Grades 1-12 (USOE Cooperative Research Project # 1680), New York State College of Agriculture, Cornell University, 1965 (ERIC Document # ED 003 818). Aimed at grades 4-14. Multiple-choice. Tests for a variety of forms of (deductive) conditional reasoning.
The Cornell Conditional-Reasoning Test, Form X is a test that can be used for assessing critical thinking skills.