San Jose State University
San Jose State University: Categorical Fun
Six logical problems are defined to challenge students to use critical thinking skills as they tackle these brain-teasers. No answers are provided, but there are some instructions for how to approach the problems.
Other
Exidor's Logic Puzzle Place
This lighthearted personal website (Exidor is a character from the old "Mork and Mindy" TV show) provides a multitude of logic puzzles and brain teasers, along with links to similar sites. Solutions provided for each puzzle.