Scholastic
Scholastic: Math Maven's Mysteries: Mystery at the Third Strike Sports Store
Solve a mystery using your reasoning skills. At this site use all the clues and figure out the winner of the Third Strike Contest.
Other
R. B. Jones: The Philosophy of Logic
Excellent overview of logic. Defines the term in informative detail, while relating logic to its neighbors in epistemology, metaphysics, and analytic philosophy. A terrific introduction to the subject.
National Council of Teachers of Mathematics
Nctm: Figure This: Thirteen? Oh No! (Pdf)
If you're superstitious you may want to try this math challenge. Test your reasoning and number sense skills by finding out if there is a Friday the 13th every year. Discover how understanding number patterns and reasoning can be helpful...
National Council of Teachers of Mathematics
Nctm: Figure This: Don't Fall In
Have you ever wondered why manhole covers are round? Believe it or not, there is a logical, mathematical reason. See if you can figure it out in this NCTM Math Challenge for Families activity. A one-page activity with suggested life...
University of St. Andrews (UK)
University of St. Andrews: Willard Van Orman Quine
Great biography of Quine. Summarizes his works in the context of his life, with numerous quotes from Quine himself.
University of St. Andrews (UK)
University of St. Andrews: Alfred Tarski
Brief introduction to Tarski's life and work. Explains the major topics in mathematics and logic on which he worked.
University of Cambridge
University of Cambridge: Nrich: Amy's Dominoes
On this one page website sharpen your logic and problem solving skills while working on this challenge. The solution is available to double check your solution.
University of St. Andrews (UK)
University of St. Andrews: Stanislaw Leshniewski
Brief biographical entry on Leshniewski detailing his relationship with Lukasiewicz.